National Astronomy and Ionosphere Center Arecibo Observatory

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A R N NEWSLETTER A R Y EC R IB TO O OBSERVA June 2003, Number 36 Photo: Jonathan Friedman and John Toohey, 2002

and from 1984 to 1985 he was assistant Robert L. Brown named as new director of NRAO operations in Tucson. NAIC Director He received his B.A. from the University With excerpts from an article in the Janu- of California-Berkeley in 1965, and his ary 23, 2003 Cornell Chronical by David M.S. and his Ph.D. from the University Brand, Copyright © Cornell University of California-San Diego, both in 1969. At News Service NRAO he has been involved in studies, both theoretical and observational, of the obert Brown, a noted astrophysi- interstellar medium, the galactic center Rcist and observatory administrator, and distant galaxies. widely experienced in international col- laboration, has been chosen as the new Bob’s intends to spend “an appre- Director of the National Astronomy and ciable amount of time at the telescope” Ionosphere Center. He took up his new and plans to make the observatory even position on May 5 succeeding Paul Gold- more accessible to the scientists who use Bob Brown smith, who stepped down on January 1 to it. This means, in his words, “providing return to full-time research and teaching a level of support that is somewhat enhanced over what has been historically (see NAIC’s November, 2002 newsletter). INDEX Don Campbell, NAIC Associate Direc- provided. We need staff to assist potential tor was Acting Director in the interim users in all phases of scientific research, New NAIC Director...... 1 period. from proposal writing to calibration and State of the Observatory ...... 2 data reduction. (…) What could expand Space and Atmospheric Sciences..... 2 Bob comes to us from NRAO and in Arecibo’s usage even further is a capabil- Radio Astronomy ...... 4 recent has played a leading role in ity for broad question-solving by letting NSF Management Review of NAIC 6 the international group that is construct- researchers anywhere access archival Solar System Studies ...... 20 ing the Atacama Large Millimeter Array data, perhaps through the National Vir- 2002 REU Summer Program...... 22 (ALMA) observatory in Chile. He has tual Observatory initiative, or by having Computer Department...... 25 been both associate and deputy director of the observatory staff undertake observa- Workshops held at Arecibo...... 26 NRAO since 1985, spearheading not only tions on behalf of specific users.” New Scheduler ...... 29 the United States involvement in ALMA Inaugural Gordon Lecture ...... 30 We extend to Bob a warm welcome but also managing NRAO participation NAIC Policy on Press Releases...... 30 in NASA’s Space VLBI Project. From to the NAIC and the Arecibo Observa- Comings and Goings ...... 30 1977 to 1980 he was assistant director tory. Literary Award for “Hijos” ...... 31 of NRAO operations in Green Bank, Job Openings...... 33 Seminars since the last newsletter. 34

The NAIC is operated by Cornell University under a Cooperative Agreement with the National Science Foundation. ing effects), validation, calibration, tion through the prospect for a broadened State of the Observatory and archival storage such that the data radar astronomy user base. Developing R. L. Brown are available for use by others. Groups ways to channel that creativity most of astronomers with common research productively is exciting. n 2003 the NAIC is in a state of transi- goals are organizing themselves as As wonderful as the new facilities tion. The Gregorian upgrade project is teams or consortia to share the effort I are, the real strength of the Observatory complete and successfully met its ambi- and the benefits from ALFA observa- is its people. In this regard the state of tious goals; receivers are available (or tions (see Workshops article, page 26). the Observatory has never been better. soon will be) for frequencies from 430 How these consortia share tasks with The Observatory staff members, in all MHz to 10 GHz, with continuous cov- NAIC to the greatest benefit of all is a occupations, are highly professional erage above 1.2 GHz; the S-band radar question to be answered. There are few and dedicated people with a clear vision system is in routine operation; the figure applicable models from which ideas may of the future and a strong commitment to of the primary mirror has been readjusted be harvested. This makes considering bringing it about. This makes me very to provide unrivaled sensitivity across the such issues exciting and important. entire spectrum for which an observing proud to be part of the NAIC as it makes capability is offered to researchers; and We have recently submitted a pro- its transition to the future. the atmospheric sciences program has posal for a new High Frequency (HF) been enriched by the dual beam radar facility that will permit atmospheric capability. This is the realization of researchers to study the interaction past planning. Looking to the future, between a powerful radio wave and the Space and Atmospheric Sciences we see ALFA as a major initiative in ionospheric plasma in a region where Sixto González radio astronomy (see NAIC Newsletter, strong Langmuir turbulence may be ur brief report for this issue begins Nov. 2002), the proposed ionospheric excited (see the following article). The with the observations over the last heating facility as a major initiative in HF facility is an ideal scientific comple- O two quarters or so. Bob Kerr and John atmospheric sciences, and the conceptual ment to the unique 430 MHz incoherent Noto (Scientific Solutions Inc.) visited design of an X-band radar system as the scatter radar in a quiet magnetic-mid- several times in this period and collabo- next major initiative in planetary radar latitude environment. The NAIC also rated with Sixto González Mike Sulzer, astronomy. There is also an opportunity provides a suite of modern atmospheric Craig Tepley, Raúl García, and Carlos now to consider longer-term initiatives optical instruments and the infrastruc- Vargas (all NAIC) to study the topside that build on, or even supplant, existing ture to support visiting scientists who and exosphere using our ISR and the capabilities leading to new “discovery bring to the Observatory additional instruments in our optical lab. For many space”. It’s a welcome, and exciting, instrumentation and other experimental of the observing campaigns the weather time of transition. requirements. HF studies at Arecibo tie together aeronomy, space physics, was bad or there were problems with the The multi-feed ALFA receiver will plasma physics and education in a unique IR Fabry-Perot that is used for observing bring with it a new way of observing, combination that allows for an effective the He 1083 nm emission. During the new requirements for the management implementation of NSF’s strategic plan night of October 1, 2002 we observed and archiving of spectral line and con- for enhancing diversity, making state the effects of a geomagnetic storm on tinuum data bases, and an altogether of the art infrastructure available to the the topside. Figure 1 illustrates some new paradigm for the involvement of the community, and providing opportunities of the results including: 1) evidence for scientific community with NAIC. ALFA for advance discovery and understanding two strong poleward surges in the ther- is much more than a receiver capable of of science and engineering. Altogether, mosphere, 2) spread-F conditions right generating 7 times as much data in the it’s an exciting prospect. before sunrise, and 3) an He+ layer that 21-centimeter band as the existing single- rose and fell in synchronization with the beam receivers. It allows astronomers to The planetary radar program is being F-region motions. Another campaign develop projects that necessarily require transferred from NASA sponsorship to occurred in late March 2003 followed mapping large regions of the sky; in some the NSF astronomy research portfolio. by a short campaign in early May. cases these will be the sort of exploratory By necessity, this transfer provides In the most recent campaign, Bob research that the Arecibo telescope has an opportunity to reassess goals as Kerr was at Arecibo for about a week to proved to be so successful in promoting it removes pre-existing constraints. study the twilight decay of the O+ 732 nm in the past. But the enormous ALFA data Among the ideas to be considered are thermospheric emission. Together with rate also requires astronomers to think moving the radar to a higher frequency, Craig Tepley and Raúl García, Kerr used in terms of automated systems for data X-band, to achieve even better angular our facility’s Fabry-Perot interferometer taking, data filtering (for RFI, spectral resolving power. The move to NSF also and Ebert-Fastie spectrometer to measure baseline instabilities or other corrupt- brings with it further creative stimula- the O+ linewidth and intensity during

June 2003, Number 36 2 NAIC/AO Newsletter June 2003, Number 36 3 NAIC/AO Newsletter goals of the TIMED project are twofold: 0.54 Storm-induced variations in the He+ fraction first, to validate the TIMED observations 2000 in the Topside ionosphere and the electron 0.44 He through cross-calibrations with ground- + 1500 density in the F region show correlation. 0.33 Fraction based instruments, of which Arecibo is 0.23 one of many; and second, to coordinate 1000 Height (km) 0.13 with TIMED observations in an attempt 500 to resolve a number of open questions 0.026 22 23 00 01 02 03 04 05 06 07 regarding D- and E-region ionosphere 5.67 500 phenomena. The scientific questions

October 1-2, 2002 (evening to morning) 5.25 Log 450 include: 1) the ion composition of the

4.83 10 D-region, 2) tides and waves in the 400 of Electron Density 4.41 mesosphere including their latitudinal 350 4.00 extent and evolution, and 3) the wind 300 3.58 shear mechanism for the formation of 250 3.16 Height (km) Es layers. 200 2.74 2.32 Diego Janches continued his regular 150 1.90 meteor observations in the months of 100 1.49 October through December 2002 and 22 04 05 06 07 08 Time (AST) then again in May 2003. In March, he did a great job hosting the meteor work- 500 shop described in this issue (page 27). 400 Also in March we received a visit from 300 Paloma Farias Gutierrez and Johannes

200 Wiig (PSU) who came to install a new Height (km) 100 all sky imaging system. John Mathews’ group at PSU assembled this system Electron density/tick interval: .2x1011 m-3 using NSF funds. It is intended to be a user owned public access instrument, and Figure 1: Shown are the effects of a moderate geomagnetic storm on the ionosphere over Arecibo. The bottom we expect to have the images available panel shows high resolution (600 m) profiles of the electron density at the times when we had the peak distur- on-line soon. bance (05-06 local time). The middle panel shows the effects of what appear to be two poleward surges in the thermospheric neutral wind, driving the F-region peak down to 250 km at midnight and then again right after Ulf von Zahn (IAP Kühlungsborn, 0300 local time and the irregularities that occur after 0500 local time. Finally the top panel shows how the Germany) visited for a little over a week + He layer responds to the F region variations. at the end of October 2002. In February several evening and morning twilight Qihou Zhou (Miami University), and March 2003 Peter Menzel (IAP & periods. Skies were generally good, Jonathan Friedman, Craig Tepley, and U. of Rostok) visited to help establish allowing us to gather a reasonable data Shikha Raizada (all NAIC) have been daytime observations with the K lidar. set for this particular experiment. The carrying out observations in support Also in February, Josef Höffner (IAP) purpose of the study was to look for pos- of the NASA TIMED (Thermosphere visited for a little over a week to discuss sible evidence of so-called, “hot oxygen” Ionosphere Mesosphere Energetics and the global structure of the mesopause at low-latitudes. Dynamics) satellite. These observations metals layer and climatology. Lara include two short (8-hour) validation runs Waldrop (Boston Univ.) and Farzad We supported World Day studies each month and two multi-day periods Kamalabadi (Univ. Illinois) visited in in October, November, December and during the solstices to achieve their sci- March. Lara is helping with the analy- March. The March World Day was a ence goals. sis of some of the data from the topside ‘floating’ world day and was moved campaigns described above, and Farzad in response to two X-class solar flares The first set of observations were is collaborating with our radio science that occurred on March 17 and 18. The in early January 2003, and the first group primarily in the area of optimal observations were successful and we solstice campaign was held from Janu- inversion of our ISR data. thank all the inconvenienced observ- ary 28 to February 3 in conjunction ers who agreed to be ‘bumped’ off the with mesopause metals observations We recently improved our lidar capa- schedule, which caused them a delay of of Jonathan Friedman, Craig Tepley, bilities by installing a second (new) dye almost a week. Shikha Raizada, and Qihou Zhou, along laser in April. That allows us to study with Rubén Delgado (UPR-Río Piedras) three metallic species simultaneously. and Diego Janches (PSU/NAIC). The We pump the two dye lasers by splitting

June 2003, Number 36 2 NAIC/AO Newsletter June 2003, Number 36 3 NAIC/AO Newsletter the Nd:YAG laser beam. This somewhat 3. On a related note, during the month of decreases the output power from each March we installed and tested a model Radio Astronomy Highlights dye laser, so we plan to compensate by 5773 klystron. We had no problems Compiled by Chris Salter improving the signal-to-noise ratio with in the installation and obtained full modifications to the receiver systems. power immediately. (For those not The augmented instrumentation gives us familiar with these tubes, they are an The Brightest Pulses in the Observ- an opportunity to study Ca and Ca+ simul- updated high efficiency version of able Universe: Observations of Giant taneously, which is essential to compre- the ‘classic’ model 3403’s we have Pulses from the Crab Nebula hend the complex metal chemistry of the been using for more than 20 years.) he Crab Nebula Pulsar is famous upper mesosphere. Apart from this, we We have over a dozen of these tubes Tfor its sporadic emission of ‘giant’ can also study differences between the that we obtained from Clear Air Force pulses. With individual examples reach- occurrence of sporadic layers in alkali base in Alaska (see November 2002 ing brightness temperatures as high as metallic layers and non-alkali species, NAIC newsletter), and so for the first 1032 K in µs resolution observations, and such as Fe, by sampling the common time in may years the ‘spare tube’ much higher (~1037 K) at nanosec resolu- volume in space. situation is well in hand. We are cur- tions, the Crab Pulsar’s giant pulses are rently considering the best strategy Finally a summary of news from our the brightest known pulses in the observ- for tube usage. Should we continue Radio Science group: able Universe. Their study is rewarding using our old 3403s since they might in many ways, and they represent impor- 1. The proposal to reestablish our HF not work after a prolonged storage, tant evidence for theories of the pulsar ionospheric interaction facility men- or should we realize the benefits of emission mechanism. In addition, they tioned in the “State of the Observa- higher efficiency operation immedi- serve as especially sensitive probes of tory” article was submitted in April ately? the pulsar’s host, the Crab Nebula. Fur- 2003. We are currently finalizing a 4. We continue our development of our thermore, the Crab Pulsar may signify sub-contract for the final electrical digital receiver project. The LINUX the presence of other source classes in design of the facility (antenna feed, driver for the Echotek card we have the transient radio universe that could transmission lines, baluns, etc.), the purchased is done, and preliminary represent targets for proposed widefield completion of which, simultaneous tests have been successful. We hope telescopes such as LOFAR and SKA. with the proposal review process, will to do an initial test with real data allow the earliest completion date if Of the over-1400 known , the during the summer and have an IF the project is funded since the final Crab Pulsar is remarkable for the highly sampling, digitally filtered data taking checks on the design will occur at an atypical nature of its pulse profile; spe- system in place in the fall of this earlier date. These checks include cifically, for the peculiar, highly unusual, for use in at least a few modes. We structural safety studies and evalua- frequency dependence of its pulse are currently designing the software tion of the impact of operation on the structure. In order to characterize the for data collection. We have deter- AO facility. detailed spectral dependence of its pulse mined that the first feature that we components, and the rates of occurrence 2. Our program to modernize the vener- need is a “digital oscilloscope”. The and statistics of the giant pulses, Jim able 430 radar system continues. We old-fashioned but essential radar “A Cordes (Cornell), Ramesh Bhat (MIT), are currently obtaining the best per- scope” is no longer effective at the Tim Hankins (NMT), Maura McLaugh- formance we have enjoyed in years analog level since the bandwidth is lin (Jodrell) & Jeff Kern (NMT) have for single beam operation from the too wide. Therefore, it is necessary to conducted an extensive multi-frequency carriage house, but some more work display the digitally filtered data (or at campaign of the Crab Pulsar at Arecibo, needs to be done to achieve similar least selected subsets of it) in a mode using all available Gregorian-dome performance in dual beam mode. In similar to the standard “A scope”. receivers, as well as the Observatory’s particular, we need a second very fast-dump, real-time correlator system, good monoplexer (the device which the Wide-band Arecibo Pulsar Proces- serves as the final protection for sor (WAPP). Data were taken over a the receiver front end) so that both frequency range from 0.43 to 8.8 GHz systems will have the lowest system at time resolutions of ~10–100 µs, from noise over the full altitude range and Jan – May 2002. This has led to several will operate reliably under all con- interesting results pertaining to the nature ditions. We expect this work to be of the giant pulses and their frequency completed over the summer. dependence, and valuable insights into

June 2003, Number 36 4 NAIC/AO Newsletter June 2003, Number 36 5 NAIC/AO Newsletter dNGP/dø dNGP/dø

dNGP/dø dNGP/dø

dN /dø GP dNGP/dø Amplitude and Number of Giant Pulses

dN /dø GP dNGP/dø Pulse

dNGP/dø dNGP/dø

−0.5 0 0.5 −0.5 0 0.5 Pulse Phase (cycles)

Figure 1: Total intensity profiles of the Crab pulsar at 10 radio frequencies. Figure 2: The intensity against time and frequency, showing a single dis- The pair of plots for each frequency is the standard average intensity profile persed giant pulse as it arrives at different frequencies centered on 430 (top) and a histogram of counts of giant pulses plotted against pulse phase MHz. The right-hand panel shows pulse amplitude vs frequency, while the (bottom). A threshold of 5σ was used to obtain giant pulses included in the bottom panel shows the pulse shape with and without compensating for histograms. The total integration time is given in the top frame and a horizontal dispersion delays. This pulse is the brightest in 1 hr of data. The segments bar shows the net instrumental time resolution; the bar length is 10 times the at either end of the bandpass, where the pulse arrival time is the opposite actual resolution. (Courtesy: Ramesh Bhat) of the trend at most frequencies, is caused by aliasing of the signal. (Cour- the influence of the Crab Nebula on the The high time and tesy: Ramesh Bhat) pulsar’s radio emission. frequency resolutions The PSR J0407+1607 Binary System inherent in the data enabled these observ- The observations show that giant ers to identify and quantify frequency Since Feb 2002, Dunc Lorimer (Jodrell), pulses occur only in the main pulse (MP) structure in individual giant pulses using Kiriaki Xilouris (UVA), Andy Fruchter and interpulse (IP) components, and that a scintillating, amplitude-modulated, (STScI), Ingrid Stairs (UBC), Fernando giant pulses ‘follow’ the IP in pulse phase polarized shot-noise model (SAMPSN). Camilo (Columbia), Ángel Vázquez & Jo as it shifts to earlier phases above ~4 GHz The frequency structure is unresolved at Ann Eder (NAIC) have been carrying out (Fig. 1). This may suggest that the same and below 1.5 GHz, but well-resolved regular timing observations of the binary physical region is responsible for both between 2 and 4 GHz. Further, the fre- msec pulsar, J0407+1607. As detailed in the low-frequency and the shifted high- quency structure associated with mul- NAIC Newsletter No. 34, this pulsar, dis- frequency IP. Further, there is strong tipath propagation decorrelates on very covered in a drift-scan survey by Fruchter evolution of the relative strengths of the short timescales (~25 ± 5s at 1.5 GHz). in 1994, is a 25.7-ms pulsar in a 669- MP and IP as a function of frequency; day orbit about a low-mass (~0.2 M ) These measurements imply a scintilla- 8 specifically, the ratio of peak IP to peak tion pattern speed ~540 kms−1, or 3 times companion. Prior to the present timing, a MP steadily decreases from 0.43 to 2 larger than the transverse pulsar speed phase-connected timing solution had not GHz, stays low from 2.5 to 3.5 GHz, from HST measurements. been possible due to the irregular spacing and rises at higher frequencies such that The most plausible interpretation is that of observations, and the large covariances the IP is much stronger than the MP at 8.8 the multipath propagation is strongly between the orbital parameters and the GHz. The strongest giant pulse observed influenced by the Nebula filaments, thus pulsar position. A solution has now been (at 0.43 GHz), with a peak flux density providing useful constraints on filament obtained thanks to the independent detec- ~130 times the flux of the Crab Nebula motions. For example, pulsar-filament tion of this pulsar at Parkes by the McGill (or ~155 kJy), has signal to noise ratio distances of ~1 pc would imply trans- pulsar group (Scott Ransom, Jason Hes- of 1.1 104 (Fig. 2). With the Arecibo- × verse filament speeds of ~18 kms−1, sels, Mallory Roberts & Vicky Kaspi). WAPP combination, the brightest giant and even larger motions for the case of Follow-up Arecibo observations by that pulses are potentially detectable (5- ) to σ combined effects of filaments and the group have resulted in a refined position, distances of ~1.6 Mpc. intervening ISM. allowing the present observations to be

June 2003, Number 36 4 NAIC/AO Newsletter June 2003, Number 36 5 NAIC/AO Newsletter NSF Management Review of NAIC R. L. Brown he five year Cooperative Agreement between the National Science Foundation (NSF) and Cornell University for “Support Tof the National Astronomy and Ionosphere Center for Research in Radio and Radar Astronomy and Atmospheric Science” began October 1, 1999 and will expire September 30, 2004. The governing body of the NSF, the National Science Board (NSB) has recently affirmed its desire that NSF facility management Cooperative Agreements be treated by the NSF with the same competitive, peer-review, process as are research proposals from individual investigators. Here the intent, as with research proposals, is to assure that NSF support is given to those programs that provide the greatest potential for scientific innovation as judged by the scientists most involved in the research fields most affected. To achieve this end, the NSB has stated its position that the decision to award a Cooperative Agreement should result from a competitive process. The NSF has implemented this directive in three steps. In the first step, the NSF conducts a management review using knowledgeable outside consultants to establish an objective assessment of the role of its facilities, of the community of users each facility serves, of the development plans for the facility as formulated by the facility management, and of the effective- ness of the organization that manages the facility. In the second step, the NSF uses the report of the management review to draft material describing the facility and the NSF goals for the facility to be included in an open solicitation for proposals from organizations interested in operating the facility. The third and final step is the peer-review competition when an NSF- convened panel of scientists and management experts assesses the proposals and makes an award recommendation to the NSF. That recommendation is reviewed by the NSF Director and forwarded with the Director’s comments to the NSB for a decision. NAIC has completed the first phase of this process. The NSF Cornell/NAIC Management Review Committee met on December 18/19, 2002 at the Arecibo Observatory. The committee was chaired by a knowledgeable Arecibo user, Professor W. Butler Burton, recently retired from the University of Leiden in the Netherlands. Presentations were made by Cornell University officials, Observatory department heads and others. Although it was very difficult in the brief period that was allocated to the presentators to communicate the full scope of activities, progress, plans and problems for any aspect of the Observatory operation, each of the speakers uniformly conveyed a frank and thorough assessment of his or her activity or involvement that was greatly appreciated by the committee. The committee report has been submitted to the NSF. Over the next approximately 15 months we expect the next two phases of the NSF competitive procurement for the NAIC Cooperative Agreement to occur. We expect this activity to have very little impact on Observatory operations; hopefully it will be invisible to Arecibo users. But the result of this important process, we believe, will lead to a better understanding by the NSF of the unique scientific capabilities and potential of the Arecibo Observatory, and of the research community it serves, that will manifest itself in an increased commitment by the NSF for support of NAIC. If so, Arecibo users will certainly see, and benefit by, that renewed commitment. properly phase connected. The resulting forward and including the earlier timing been confirmed in the survey of over timing residuals now span over 450 days data. Work on achieving this is now in 1000 deg2. and are shown in Fig 3. progress. Highlights include a 55.7-ms pulsar, Using the new solution, the orbital J0609+2130, for which an ephemeris eccentricity of this system is now The Timing of Upgrade Drift-Scan has now been obtained, two msec pul- known to reasonable precision (0.00097 Pulsars sars (still under investigation) and sev- ± 0.00002) and is in line with theoretical Dunc Lorimer, Maura McLaughlin eral bright long-period pulsars. Early predictions for long-period binary pul- (Jodrell), Zaven Arzoumanian (GSFC), suspicions that PSR J0609+2130 was sars (e.g. Phinney, 1992, PTRSA, 341, Kiriaki Xilouris (UVA), Jim Cordes a relatively young pulsar (see Newslet- 39-75). Further, like the 635-day binary (Cornell), Don Backer (Berkeley), ter No. 35), proved to be incorrect. Its pulsar J2016+1947, discussed by Freire Andrea Lommen (Franklin & Marshall) timing solution, now spanning almost a et al. in Newsletter No. 35, J0407+1607 & Andy Fruchter (STScI) have begun year, show it to be old (characteristic age will provide an excellent test of general timing observations for the new pulsars ~2 Gyr) with a relatively weak magnetic 9 relativity and in particular the strong discovered by the Arecibo PSPM drift- field (5× 10 G). J0609+2130 is similar equivalence principle. This test, along scan surveys described in NAIC Newslet- in many respects to J2235+1506, discov- with other follow-up work, requires an ter No. 35. So far, 11 new pulsars have ered in a pre-upgrade drift-scan survey extension to the current timing solution (Camilo, Nice & Taylor, 1993, ApJ, 412, by increasing the existing timing baseline p. L37) and thought to be a relic of a

June 2003, Number 36 6 NAIC/AO Newsletter June 2003, Number 36 7 NAIC/AO Newsletter Neftalí Sotero (UPR), window. Unlike the other two MP com- 2 50 Ramesh Bhat (NAIC) & ponents, which frequently exhibit short

) Dunc Lorimer (Jodrell) drifts in both directions, this component have undertaken a study never seems to show any trends of drift- of several bright pulsars in ing. 0 0 the Arecibo sky for details The IP structure is clearly double, and related to the mode-switch-

Pre-fit Residual (µs is in agrement with the result of Everett &

Residual (milli-periods) ing, nulling and drifting Weisberg (2001, ApJ, 553, p. 341) from phenomena. Analysis also pre-upgrade observations. The first com- -2 -50 aims at the integrated pro- ponent is always the weaker, although it files and their relationship 2002 2002.5 2003 appears more often than the second (Fig. to locations of emission Date 6). Further, there is evidence for a new, regions in the magneto- third component that is most prominent Figure 3: Timing model residuals for observations of PSR J0407+1607. spheres of pulsars. In the in the weakest pulses, in which there is All data shown were taken with the PSPM at a center frequency of 430 first phase of the project, MHz. (Courtesy: Dunc Lorimer) only a trace of the other 2 components. 1175-MHz observations The bridge of emission between MP and disrupted double neutron- binary have been made of 5 pulsars IP seems to be fairly stable in its strength, system (i.e. a “failed” Hulse-Taylor using the WAPP backend. This combina- and is most prominent in the weakest binary pulsar!). Of the long-period pul- tion of frequency and backend is the most pulses. It remains a puzzle whether the sars found so far, the most interesting is sensitive currently available for Arecibo MP and IP are emitted from 2 opposite J0815+09, it having a most unusual pulse pulsar studies. Observations were made magnetic poles (nearly orthogonal rota- profile (Fig. 4, left) which defies standard in polarimetric mode, since one of the tor) or from one pole (nearly aligned rota- classification schemes e.g.( Rankin, ApJ, goals is to attempt single-pulse polar- tor), where the geometry of the emission 1993, 405, p. 285). Single-pulse PSPM imetry of these pulsars. Analysis and region is such that there are 2 maxima per data show an extremely ordered pattern interpretation are currently underway. period. Adopting the more commonly in the individual pulses (see Fig 4, right). Several new results have emerged favored model of an orthogonal rotator, The unusual profile morphology and the from studies of intensity dependence of our results suggest that the weaker pulses drifting subpulse behavior are under the pulse structure and stability, illustrated are emitted from higher altitudes in the further study as the timing observations in Figs. 5 & 6 for PSR B0950+08. This magnetosphere. continue. pulsar shows both a main pulse (MP) and interpulse (IP); the former is composed of The Arecibo 430-MHz Intermediate New Details of Single Pulses and 3 components and the latter 2. The third Latitude Pulsar Survey Average Profiles for PSR B0950+08 component of the MP dominates the aver- age profile of the strongest pulses, which Between 1989-91, the 430-MHz Car- The wideband Gregorian receivers and is narrower than the average profile of all riage-House receiver (430-CH) was new pulsar backends of the Arecibo tele- data. In contrast, the average profile of used by José Navarro (then Caltech) to scope open up new avenues for single- the weakest pulses is dominated by the carry out a pulsar survey at intermediate pulse pulsar studies of unprecedented second component, and is broader than Galactic latitudes (i.e., 7° < |b| < 20°). quality. Leszek Nowakowski (UPR), the average pro- The motivation for such a survey is that file. A histogram the number of msec pulsars detectable analysis (Fig. 6) from Arecibo at 430 MHz is predicted to 327 MHz of the locations be maximal near b ~ 20° (e.g., Cordes & of these com- Chernoff, 1997, 482, p. 971). This Inter- ponents reveals mediate Latitude Survey (ILS) covered 430 MHz that the first 130 deg2 of sky. A total of 6121 pointings MP component, were made, each of 66.4 s duration. The albeit prominent data analysis was completed in 1993, pro-

1400 MHz in the weakest ducing 4 detections of previously known pulses (up to 6% pulsars and 13 new pulsar candidates. of the strength It was only in Dec 1997, when the 0 180 360 120 240 of the strongest Longitude (degrees) Longitude (degrees) telescope was again able to point post- pulses), is highly upgrade, that Stuart Anderson (Caltech), Figure 4: Left: Integrated pulse profiles for J0815+09 at 327, 430 & 1400 MHz. Right: stable in its phase Zoom-in of single pulses at 430 MHz showing the ordered behavior of the 4 distinct using 430-CH and the PSPM as back-end, within the pulse components. (Courtesy: Dunc Lorimer) confirmed the first 6 new pulsars from

June 2003, Number 36 6 NAIC/AO Newsletter June 2003, Number 36 7 NAIC/AO Newsletter PSR J1814+1130 PSR J1819+1305 PSR J1828+1359 10

9

8

7 Flux Density (mJy) 6 Flux Density (mJy) Flux Density (mJy)

5 0 0.25 0.5 0.75 1 0 0.25 0.5 0.75 1 0 0.25 0.5 0.75 1 Rotational Phase Rotational Phase Rotational Phase 4 PSR J2016+1948 PSR J2017+2043 PSR J2048+2255 3

2

1

100 200 300 400 200 300 400 500 600 700 800 Pulse Phase (sample numbers) Pulse Phase (sample numbers) Flux Density (mJy) Flux Density (mJy) Flux Density (mJy) Figure 5: Average pulse profiles of PSR B0950+08 obtained by integrating single pulses in different intensity bins, the limits for which are chosen such that equal number of pulses 0 0.25 0.5 0.75 1 0 0.25 0.5 0.75 1 0 0.25 0.5 0.75 1 Rotational Phase Rotational Phase Rotational Phase fall into each bin; the analysis is performed for both the full pulse period (right) and for the longitude range of the IP PSR J1756+18 * PSR J1837+1221 * PSR J2050+13 * (left). The integrated profile obtained from all data is overlaid (black) for comparison. The pulse intensity increases from bottom to top, and the profile from the weakest pulses (bin #1) reveals at least one, previously unknown component of the IP. (Courtesy: Leszek Nowakowski) Flux Density (mJy) Flux Density (mJy) Flux Density (mJy)

0.9 0 0.25 0.5 0.75 1 0 0.25 0.5 0.75 1 0 0.25 0.5 0.75 1 Rotational Phase Rotational Phase Rotational Phase 0.8 Figure 7: 430-MHz pulse profiles for the 9 pulsars found in the Arecibo Intermediate Latitude Survey. 0.7 (Courtesy: Paulo Freire) 0.6 150 200 250 300 350 Pulse Phase (sample numbers) 0.5 7 and 300 × 106 yr and rotational One of the isolated ILS pulsars, 0.4 periods between 284 and 1060 PSR J1819+1305, (P = 1.06 s, DM = 0.3 ms. However, the remaining 64.9 cm−3 pc) was later discovered inde- 0.2 pulsar, PSR J2016+1947, has a pendently in a Parkes survey (Edwards

0.1 rotational period of 63.9 ms, and et al., 2001, MNRAS, 326, 358). Paulo 9 0 a characteristic age > 1.8 × 10 now finds that the object nulls for about 150 200 250 300 350 200 300 400 500 600 700 800 Pulse Phase (sample numbers) Pulse Phase yr. This pulsar is part of a binary 50% of the time. The nulls exhibit a

Figure 6: Histograms of the locations of intensity maxima of system with a 0.3-M8 white- remarkable periodicity of about 53 rota- single pulses; right: for the full pulse period, left: for the longitude dwarf companion. The orbital tions. The emission characteristics of this range of the IP. The average profile obtained from all data is period is unusually long for such pulsar are now being studied in more overlaid (black). The upper left panel shows separate histograms a system, 635 days, and the orbital detail by Deshpande & Rankin. for the weak and strong pulses (red and black, respectively), eccentricity is ~0.0012. Timing of where the limit is set such that equal number of pulses fall into Discovery of PSR J1837+1221 in this binary system was resumed the two groups. The lower left panel shows the histogram of all the same Parkes survey, coinciding in by Paulo Freire (NAIC) in Jul data (red); its bimodal nature re-affirms the presence of the 2 position, period and DM with one of components of the IP. Additionally, it is evident that the stronger 2002, with the aim of conclu- the 7 ILS candidates not confirmed in interpulses arrive at the phase of the first component of the IP, sively determining its orbital 1997, motivated Paulo to try confirm- with the weaker ones at the phase of the second component (see parameters and characteristic ing the other 6 candidates. So far, 2 also Fig. 5). (Courtesy: Leszek Nowakowski) age, made especially difficult by new pulsars have been confirmed (Fig. the long binary period. Once these the ILS, PSRs J1814+1130, J1819+1305, 7): PSR J1756+18, (P = 0.744 s, DM J1828+1359, J2016+1947, J2017+2043 are determined, new and more stringent = 71 cm−3 pc) and PSR J2050+12 (P = & J2048+2255 (Fig. 7). These were upper limits on the violation of the Strong 1.220 s, DM = 52 cm−3 pc). It is unclear Equivalence Principle will probably be timed for 2 yr, some until early 2000, why these were not confirmed in 1997, obtained (see Newsletter No. 35). revealing that 5 are normal, isolated but telescope pointing was certainly poor objects with characteristic ages between then following upgrade work. These 2

June 2003, Number 36 8 NAIC/AO Newsletter June 2003, Number 36 9 NAIC/AO Newsletter pulsars are now being timed at 327 This has been confirmed to be the case for pulsar surveys, there is every reason to MHz. The larger bandwidth and lower several well-known pulsars. Hence, the be optimistic about the opportunities that frequency, plus the larger beam (which 327-MHz receiver increases the distance would result from the discovery of many reduces problems related to uncertainties to which a given pulsar is detectable by new recycled pulsars. An all-sky 327- in the pulsar position) all contribute to a factor of ~ √2 compared to the 430-CH MHz survey would also be a supreme better detections for these 2 pulsars. For system. The volume being covered by a probe of the local interstellar medium, this reason, 327 MHz will be used for 327-MHz survey is thus ~ (√2)3, or ~2.8 and the low end of the pulsar a new Arecibo drift-scan pulsar survey times, that of a 430-CH survey. As the function. (see below). HPBW is larger at 327 MHz (15´) than with 430-CH (9´), a 327-MHz drift-scan The ILS and the Swinburne Interme- survey should detect up to three times The Most Perfect Circle in the Uni- diate Latitude Survey detected an average more pulsars per unit time as the prolific verse of 1 recycled pulsar per 14 detections, Arecibo 430-CH drift-scan surveys, PSR J1738+0333 is a msec pulsar a proportion similar to that of previous while needing only 0.6 times as many of 5.85-ms rotational period. It was 430-MHz Arecibo surveys of the Galactic beams to cover the Arecibo sky. discovered in 2001 in a high Galactic disk. This seems indicative that the basic latitude survey made with the 20-cm assumption that motivated these surveys A critical question is that of RFI. multi-beam receiver at Parkes by Bryan (more recycled pulsars at the intermedi- Observations by Paulo show that, surpris- Jacoby (Caltech) & Matthew Bailes ate latitudes) is not founded in reality. ingly, the situation is considerably better (Swinburne, Australia). It is now being This might indicate that the scale height at 327 MHz than at 430 MHz, further timed at Arecibo by Paulo Freire. for recycled pulsars is larger than previ- enhancing the potential of this receiver ously thought, and these results will have for pulsar searches. Such a survey also This pulsar is a member of a binary

to be incorporated in future studies of the has the advantage of easy scheduling; system with a 0.1-M8 white dwarf com- Galactic pulsar population. any gap in the schedule is useful for the panion. Of all the pulsar-white dwarf survey. binaries in the Galactic disk, this has the second shortest , only 8.5 The Arecibo 327-MHz Pilot Drift- Another recent development making hr. Parkes measurements indicate that its Scan Pulsar Survey a 327-MHz survey possible is the high eccentricity is < 10−5. This is not extraor- A new pulsar survey began on 26 Apr, spectral resolution enabled by the WAPP 2003, the Arecibo 327-MHz Pilot Survey spectrometers. Using 1024 channels of Paulo Freire (NAIC), Dunc Lorimer, and a 256 µs sampling time, this survey Maura McLaughlin (Jodrell), Jim Cordes retains sensitivity to msec pulsars with −3 (Cornell), Ramesh Bhat (MIT), Michael DMs up to 100 cm pc. The large data Kramer & Andrew Lyne (Jodrell). This volumes generated can easily be stored survey is made possible by several recent on Mammoth-2 tapes. Data from the advances. One is the installation of the present survey will be analyzed at 327-MHz receiver, which has a band- Jodrell Bank, where Dunc Lorimer & width of over 30 MHz, compared to the Maura McLaughlin have considerable 10 MHz available with the 430-MHz experience analyzing Arecibo drift-scan Parkes line-feed (430-CH) system. However, data with the COBRA Beowulf cluster. the telescope gain with the 327-MHz Some data will also eventually be pro- system is only 11 K/Jy, compared to 20 cessed at Cornell by Paulo Freire & Jim K/Jy for 430-CH. Cordes. The combination of system tem- If the results of the small-scale pilot peratures, gains and bandwidths makes survey confirm the predictions, then a these two receivers equally sensitive, in 327-MHz all-sky survey, complementary the sense that for the same integration to the ALFA pulsar surveys of the Galac- time, a continuum source with the same tic plane, could be considered, possibly flux density at the two frequencies would carried out using the resources of the Arecibo Figure 8: Pulse profiles of PSR J1738+0333 at 1400 produce detections with similar signal-to- ALFA pulsar consortium. Such a survey could potentially find hundreds of new MHz from Parkes and Arecibo. The Parkes profile noise ratios. However, pulsars are steep was obtained by summing the best profiles. The Are- spectrum sources; generally, their flux pulsars, and many dozens of recycled cibo profile is a 30-min integration with a 100-MHz densities at 327 MHz are about a factor objects. It could also cover scheduling bandwidth. The horizontal bar indicates the time of two larger than at 430 MHz, producing gaps for many years to come. Given the resolution of the Arecibo experiment (sampling time similarly enhanced signal-to-noise ratios. history of past Arecibo high-latitude 64 µs). (Courtesy: Paulo Freire)

June 2003, Number 36 8 NAIC/AO Newsletter June 2003, Number 36 9 NAIC/AO Newsletter dinary, as the eccentricity predicted for Such circularity, if very well deter- kinematic methods since the regions this type of system by models that mined for a set of tight binary pulsars, is are highly obscured by interstellar dust, describe MSP formation is of the order interesting for several reasons. It allows i.e. photometric determinations are of 10−7. However, because of Arecibo’s measurements of the most fundamental not possible. The kinematic method to much larger collecting area, plus the new properties of spacetime, like the Lorenz determine distance is based on the axially L-wide receiver and the option of using 4 invariance, which is really a statement symmetric velocity field of the galactic WAPPS simultaneously, Arecibo timing that empty spacetime is isotropic and plane as described by the rotation curve measurements can now be much more has no preferred reference frames. If Θ(R) (e.g. Brand & Blitz, 1993, A&A, precise (see Fig. 8). it is not, then either the motion of the 275, p. 67). The inversion of such a binary relative to the preferred frame, velocity field, for a given LSR radial These timing measurements aim at or the anisotropy of space itself, should velocity, gives a unique solution for the determining the binary’s precise posi- induce an eccentricity along the direction galactocentric distance (GD). However tion, enabling studies at other frequen- of motion and/or along the direction of the LSR distance has two solutions for cies, measurement of proper motion the spacetime anisotropy (Bell, J., 1999, sources located at GD < GD . This and, if possible, the system parallax. source Pulsar Timing, and is commonly referred to as the distance They also aim at the possible measure- the Internal Structure of Neutron , ambiguity problem. ment of a relativistic effect, the Shapiro p. 31). It should be noted that no physical delay, from which the inclination (i) of Araya et al. (ApJS, 2002, 138, p. theory of the nature of spacetime capable the orbit and the masses of both compo- 63; see also NAIC Newsletter No. of explaining the relativistic motion of nents of the system can be obtained. To 31) observed the recombination line binary pulsars questions these basic date, this effect has not been measured H110α (4874.15 MHz) and the H CO principles (Esposito-Farèse, 1999, 2 for this system, and the inclination of J =1 – 1 (4829.66 MHz) transition Pulsar Timing, General Relativity and KaKc 11 10 the orbit seems to be quite small. How- to resolve the distance ambiguity and the Internal Structure of Neutron Stars, p. ever, this unfortunate fact is not entirely estimate distances to 20 ultracompact 13), but it is still a good thing to improve negative as the lack of a Shapiro delay HII regions (UCHII). The same tech- on the observational limits, as it is impos- enables a very precise measurement of nique has been used in this project for sible to foresee the predictions of future the . Including the a larger sample (54 UCHII regions in theories of gravitation. With time, this data obtained at Arecibo, this is now total). The measurements were made system might also be useful for putting known to be < −6. Knowing the with the C-band receiver using stan- 5 × 10 upper limits on the variation of the gravi- size of the pulsar orbit about the system dard ON/OFF+diode observations. Five tational constant with time, which is still center of mass projected along the line- minutes on-source was enough to detect a topic of debate in cosmology. of-sight (a = 102,000 km/sin i), they can most sources. However, some required say that the size difference between the 10-15 min on-source to improve the semi-major and semi-minor axes of the The Resolution of Distance Ambigui- signal-to-noise ratio and confirm weak orbit (given by a e2) is < 2.5 mm/sin i. ties for Inner Galaxy Massive Star- features in the bandpass. The distance Formation Regions ambiguity was resolved for 44 of the 54 With improved data processing, and sources. Fig. 9 shows a typical spectrum more high-precision data, it might be Christer Watson (Wisconsin), Esteban obtained toward one of the sources in possible to improve the measurement of Araya (UPR-RP), Marta Sewilo, Ed the sample. the eccentricity by a factor of 10. If, as Churchwell (Wisconsin), Peter predicted, no eccentricity is measured, Hofner (UPR-RP) & Stan Kurtz G35.04-0.50 (UNAM, Mexico) carried out we will then know that the orbit does 0.31 not deviate from a perfect circle by the second Arecibo Survey of 0.3 more than 25 µm/sin i, or about the size H110α and H2CO 6 cm lines 0.29 H CO a human cell. Amongst all the objects toward regions of massive star 2 0.28 known to mankind, this will probably formation in the inner Galaxy. (Jy)

The project’s main objective ν be that which most resembles an ideal, S 0.325 V geometric circle. Presently, the record was to resolve the distance α TP 0.32 H110 goes to the orbit of PSR J1012+53, ambiguity of massive star known to be circular to within 150µm forming regions located in the 0.315 (Lange et al., 2001, MNRAS, 326, p. galactic longitude range of the 0.31 274). Another system being timed at SIRTF/GLIMPSE survey vis- -100 0 100 −1 Arecibo, PSR J0751+1807, might be ible from Arecibo. VLSR (km s ) Figure 9: Spectrum of H CO (upper) and H110α (lower) toward the measured to even greater accuracy than Distances to such regions 2 PSR J1738+0333. massive star forming region G35.04-0.50. The solid line indicates are primarily determined via the tangent point velocity. (Courtesy: Esteban Araya)

June 2003, Number 36 10 NAIC/AO Newsletter June 2003, Number 36 11 NAIC/AO Newsletter −11 15 abundant than ~ 10 Norma arm relative to H lie below the 60 Scutum arm 2 10 Sagittarius arm confusion level in the mm- Perseus arm wave region. In such cases, 5 40 sensitive observations at low frequences, which 0 (kpc) 20 are less “contaminated’’ by the emission of simple -5 molecules, may help. In 0 Sewilo et al. (2003) addition, hyperfine splitting Galactic Longitude (deg) Watson et al. (2003) -10 Araya et al. (2002) Fish et al. (2002) is often negligible at high –20 Kolpak et al. (2002) frequencies, but detectable -15 –150 –100 –50 0 50 100 150 at low frequencies (HC N, -15 -10 -5 0 5 10 15 5 LSR Velocity (kpc) HC7N, etc). Hyperfine Figure 10: UCHII regions observed in this project Figure 11: Galactic longitude as a function of LSR velocity for several splitting may be used to (crosses), Araya et al. (2002, triangles), Kolpak et samples, including the present observations. The kinematics of the Per- analyze line opacities and al. (2002, ApJ, 578, 868, ‘plus’ signs) and Fish et seus arm is well resolved within the Galactic longitude range observed. al. (2003, ApJ, 587, 701, diamonds). The spiral arm Clear kinematic signatures of other spiral arms are also detected. (Cour- hence to obtain correct model of Taylor & Cordes (1993, ApJ, 411, 674) tesy: Marta Sewilo) molecular column densi- is indicated by solid lines. The solar position and ties and abundances. Galactic center are indicated by stars. (Courtesy: A C-band Spectral Scan of the Dark Christer Watson) Cloud TMC-1 In view of these advantages, Sergei Most known cosmic molecules have Kalenskii, Slava Slysh (ASC, Russia), In addition to the determination been detected in the mm-wave region. Paul Goldsmith (Cornell) & Lars of intrinsic properties of massive star This is clearly related to the fact that, in Johansson (Onsala, Sweden) observed forming regions, such as luminosity and general, the simplest (and hence lightest) the famous molecular cloud TMC-1 presence of extended radio-continuum molecules are the most abundant cosmic at low frequencies. The entire Arecibo emission, these observations allow stud- molecular species. Their most intense C-band (4–6 GHz) was observed with ies of galactic structure. The distribution rotational lines arise at mm and submm an rms sensitivity about 17–18 mK (~2 of the sources observed in this project, wavelengths. Heavier molecules with mJy). In addition, a number of selected plus other regions studied in similar large permanent dipole moments have lines within the C- and X-bands (8 – 10 works, is shown in Fig. 10. Despite the detectable rotational lines at lower GHz) were observed with longer integra- data scatter, this figure clearly shows the frequencies in the microwave bands. tion times. From the spectral scan, they presence of 3 spiral arms within the 30°– Transitions between low energy levels detected the already known H2CO, HC5N 70° galactic longitude range. The results are more favorable in terms of line & HC7N lines. However, in more sensi- of these Arecibo observations, together intensities, especially in the regions of tive observations at selected frequen- with an extended discussion, have been low or modest density (e.g., translucent cies they detected lines of C2S, C3S, recently published (Watson et al., 2003, 13 clouds) and low temperature, such as C4H, HC3N, HCC CN, HC5N, HC7N & ApJ, 587, p. 714). The results reported by inner parts of dark clouds, which are the HC9N, about half of which were detected Watson et al., in addition to recent GBT coldest gaseous clouds as they have no for the first time (Fig. 12). Their results observations, are being used by Sewilo et internal energy sources and are shielded demonstrate that low frequency obser- al. (in preparation) for further studies of from external sources by their own gas vations can be useful for the study of the kinematics and structure of the Milky and dust. cold molecular clouds. Most of the new Way (see Fig. 11). lines were detected at X-band; therefore Another reason why observations molecular observations around 10 GHz at low frequencies are needed is that seem more promising than those at lower the line intensities of molecules less frequencies.

0.2 0.1 HC5N HC N C S HC N 0.15 0.1 7 3 0.05 9 0.1 0.05 0.05 0.05 0 0 0 0

5325.3 5325.4 5640 5780.7 5780.8 8715.5 8715.6

Figure 12: Spectra of hyperfine components of the 2–1 HC5N and 5–6 HC7N lines and newly detected 1–0 C3S and 15–14 HC9N lines. (Courtesy: Sergei Kalenskii)

June 2003, Number 36 10 NAIC/AO Newsletter June 2003, Number 36 11 NAIC/AO Newsletter An unexpected result is the weakness core is magnetically supercritical. Such B is the average field strength through −21 −1 of the tentatively detected 32–22 C2S line a core must collapse if it does not have the core, and Bcrit = 0.60 × 10 cφ NH at 5402.6 MHz. The C2S column den- support from other mechanisms, such as (µG). Measurements of B and NH should sity derived from the line intensity and internal motions. If λ < 1, the magnetic be made along the symmetry axis (i.e. assuming LTE is 2×1012 cm−2, a factor of field prevents gravitational collapse along the mean field direction) of the 20 below that derived previously from regardless of the external pressure. Such core. Otherwise, B is underestimated higher frequency observations. Very dif- a core is magnetically subcritical, and it since the Zeeman effect is only sensi- 12 ferently, their C3S column density (3×10 can never form stars as long as flux freez- tive to the line-of-sight field strength, −2 cm ) agrees well with that derived pre- ing is maintained. Blos. Also, NH is overestimated if it is viously. This is most likely indicative of measured at an angle to the symmetry In many ways, the critical mass- the subthermal excitation of the 3 –2 axis of an oblate spheroid, the geom- 2 2 to-flux ratio of a molecular cloud is C S transition. etry predicted by the simplest magnetic 2 analogous to the Chandrasekhar limit. support models. Since λ ∝ N /B, both Both parameters define the stability of a H observational effects result in an over- self-gravitating system, and both param- OH Zeeman Observations toward estimate of λ. So an individual core that eters can change with time. If the mass Dark Clouds is magnetically subcritical may appear of a white dwarf eventually exceeds the Tom Troland (Kentucky) & Dick supercritical, instead. Therefore, the Chandrasekhar limit owing to accretion Crutcher (Illinois) have been carrying question of the value of λ, and hence from a binary companion, then the star out a long-term project to observe the the role of B in core evolution, must be collapses and is destroyed. If the mass- Zeeman effect in dark-cloud cores. The approached statistically via observations to-flux ratio of a molecular cloud even- observations have involved sensitive of a large number of cores. measurements of Stokes parameter I tually exceeds the critical value owing & V line profiles in the quasi-thermal to ambipolar diffusion, then the cloud Arecibo is uniquely capable of 1665- and 1667-MHz OH lines. These collapses to form stars. addressing this issue toward nearby molecular clouds via the Zeeman effect in lines have high Zeeman sensitivity and The parameter λ can be determined 4 −3 1665- and 1667-MHz OH emission lines. probe n(H2) ~ 10 cm . They aim to test observationally from Zeeman effect The telescope beam is well matched to the current “standard model” of low-mass measurements of the field strength B, and the sizes of star-forming cores within star formation — self-gravitating mag- from estimates of the (proton) column a few 100 pc. At a distance of about netically supported molecular clumps density N of a core. This possibility fol- H 150 pc (e.g. the Taurus dark clouds) the that undergo core collapse when ambi- lows from the fact that λ = B /B, where polar diffusion reduces magnetic support crit Arecibo beam samples a region 0.12 pc in central regions. 1.00 1.00 L1448 1665 MHz L1448 1667 MHz Star formation is known to occur in 0.80 0.80 molecular cores. A key question about (K) (K) 0.60 0.60 I this process is the role of the magnetic I field. Does the field control the evolu- 0.40 0.40 Stokes tion of the cores toward star formation, or Stokes 0.20 0.20 does the field play only a secondary role? The role of magnetic fields in a molecular 0.00 0.00 core is determined by the mass-to-flux 0 2 4 6 8 10 0 2 4 6 8 10 ratio M/Φ, a measure of the ratio of LSR Velocity (km/s) LSR Velocity (km/s) gravitational-to-magnetic energies. If 0.04 the core is pervaded by a poloidal field L1448 1665 MHz 0.04 L1448 1667 MHz connected to an external medium, then 0.02 (K) there exists a critical mass-to-flux ratio (K) 0.02 V (M/ ) = c /G1/2, where c is a constant V Φ crit φ φ 0.00 that depends upon the distribution of 0 Stokes Stokes mass and flux within the cloud. For a -0.02 uniform sphere, cφ = 1/2π. For conve- -0.02 nience they define λ ≡ (M/Φ)/(M/Φ) . -0.04 crit 0 2 4 6 8 10 0 2 4 6 8 10 As long as flux-freezing is maintained,λ remains constant during core evolution. LSR Velocity (km/s) LSR Velocity (km/s) Figure 13: OH Zeeman data for the L1448 dark cloud core. At the top are the 1667- and 1665-MHz Stokes I If λ > 1, the magnetic field alone cannot profiles. The panels below each I spectrum show the Stokes V spectra. The histogram plots are the observed prevent gravitational collapse, and the data, while the heavier line plot is dI/dVLSR scaled to the fitted losB value. (Courtesy: Dick Crutcher)

June 2003, Number 36 12 NAIC/AO Newsletter June 2003, Number 36 13 NAIC/AO Newsletter across. At greater distances of order a Arecibo OH/IR stars with 2MASS data in 2nd release rapid changes in luminosity follow- processed to (25-12) µm > -0.25 kpc, the beam samples a region of order 5.0 ing a He-shell flash on the core of 1 pc, comparable to the sizes of molecu- the star, the only evolutionary phase 3 4 4.0 with comparably brief changes. lar clumps containing 10 –10 M. The system temperature in the upgraded 3.0 This conclusion inverts our current paradigm. system is low (~ 40 K with the original 2.0 L-band wide receiver, now ~ 25 K with J - H the new system) for all but the highest 1.0 (25-12) µm < -0.25 Probably the Most Sensitive zenith angles. Hence, a 1-σ sensitivity of 0.0 detached 2–5 µG is reached after 10 hr integration "normal" shell VLBI Yet: The Supernova Rem- -1.0 nants in Arp 220 toward a typical molecular core. No other 0.0 1.0 2.0 3.0 4.0 The mering galaxy Arp 220 is known technique (including the Zeeman H - Ks effect in other molecular species) offers Figure 14: J-H v H-K for Arecibo OH/IR stars with 2MASS among the most intensively stud- this level of sensitivity to magnetic fields data in the 2nd release processed to (25-12) µm > −0.25. ied of extragalactic objects, and in molecular cores. Finally, instrumen- (Courtesy: Murray Lewis) for good reason. As the proto- typical luminous infrared galaxy, it tal circular polarization with the L-band 2MASS counterparts using data from exhibits extreme far-infrared luminosity wide feed is low (Heiles, Arecibo Techni- the second release. The whole 2MASS (~ 1012L ), and a wide variety of molec- cal & Operations Memo, 99-02). dataset is available as of 27th March 8 ular lines originating in an extremely 2003, and its J, H, & K magnitudes The first results from this survey dense central condensation of dusty gas. allow a J-H v H-K plot for 121 of the included a detection of the OH Zeeman It is also the prototypical OH megamaser stars. This is known to exhibit a linear effect toward the Taurus dark cloud core galaxy, and is the system in which pc- correlation for OH/IR stars, in which L1544, with Blos = +11 ± 2 µG (Crutcher scale OH megamaser features were first the most translucent shells have the hot- & Troland, 2000, ApJ, 537, p. L139). discovered. The unique status of Arp 220 test colors (small index values) ~1600 This field strength implies λ > 1, or arises because at a distance of only 76 K, and the most opaque colors ~550 K. too weak a magnetic field to support Mpc, it is the nearest example of a truly However, the patently detached shells of the cloud against gravity. Evidence has powerful IR galaxy, and the associated proto-planetary nebulae (PPN) with very been presented by others suggesting phenomena can thus be studied in greater red IRAS colors are also known to map that L1544 has infall motions and may detail than in any other such galaxy. It back along the locus, rather than extend- be collapsing. The observations of the is the focus of considerable attention in ing its red end; such shells are far more Perseus-Taurus region have now been the search for unambiguous evidence of transparent in the near-IR than their IRAS completed, and analysis is underway. starburst or AGN activity, in order to shed colors would otherwise suggest, so old An example result is the strong detection light on the ultimate origin of the quasar- PPN can have very blue near-IR colors. (as yet unpublished) obtained for L1448 like bolometric luminosity, and on the However, this reasoning can be reversed; (Fig. 13), for which B = −26 ± 4 µG. possibility of an evolutionary sequence LOS by coding the Arecibo sample of shells Observations of the Cygnus region are triggered by galaxy merger events. just beginning. relative to a (25-12) µm color threshold of −0.25, −0.30, −0.35, etc. successively, In 1996, what was then one of By the end of this project, Tom & which is a measure of the thickness of the largest VLBI experiments ever Dick will have sensitive observations of the dusty shell, one finds that MOST was conducted on Arp 220, using the magnetic field strengths toward several (~85%) of OH/IR stars map back along compact OH maser peak as a conve- dozen dark cloud cores. These data will the color locus, and therefore must have nient phase reference. This permitted enable a statistically meaningful study of detached shells. This is illustrated in Fig. continuum imaging of the galaxy with the mean value of mass-to-flux ratios in 14 with the subset having (25-12) µm > high sensitivity, revealing the existence cores and answer the question of whether −0.25. While some of the objects with of roughly a dozen unresolved sub-mJy magnetic fields control the process of star detached shells evolve immediately into point sources scattered across the nuclear formation. PPN, the majority are expected to repeat region of the galaxy. This was interpreted a cyclical mass-loss phase. The paucity as spectacular evidence of an ongoing of normal shells undergoing secularly burst of intense star formation traced OH/IR Stars with 2MASS Counter- stable, copious mass-loss while exhibit- by radio supernovae (RSN). Both the parts ing 1612-MHz masers implies that the OH maser results (Lonsdale et al., 1998, Derek Kopon (Cornell), Murray Lewis 1612-MHz emission phase in most stars ApJL, 493, p. L13) and the continuum (NAIC) & Yervant Terzian (Cornell) is very brief. Consequently, most heavy results (Smith et al., 1998 ApJL, 493, p. identified 134 (32%) of the Arecibo mass-loss from AGB stars is seemingly L17) have significant implications for OH/IR stars (0° < Dec < 38°) with tied to developments accompanying the the field. However, these studies were

June 2003, Number 36 12 NAIC/AO Newsletter June 2003, Number 36 13 NAIC/AO Newsletter the intensity and range from 1 day to about 1 month). luminosity of star Long-term monitoring is designed to formation activ- measure or constrain accelerations in ity. By probing OH lines due to orbital motions in gas. the luminosity As is seen in nearby OHMs, the masing function of these gas often appears in the form of a torus RSN more deeply suggesting a large concentration of mass, with the new and accelerations in lines combined with observations, and some information about the geometry of combining the the masing gas can indicate a geometri- data from several cal distance, as it has in the water-maser Figure 15: The nuclear region of Arp 220 imaged with continuum VLBI at 18 cm. epochs to develop galaxy NGC 4258. Short-term monitor- The angular resolution is roughly 4 milliarcsec (~1.5 pc), and the image is 1.6 arcsec accurate light ing constrains the size scales of variable across. Two clusters of point sources are visible, separated by about 1 arcsec, and corresponding to the twin nuclei in Arp 220. These sources are interpreted as radio curves, a refined and quiescent masing regions and pro- supernovae associated with an intense nuclear starburst. This is possibly the most estimate of the vides strong constraints on maser models sensitive VLBI image ever produced, with an RMS noise level of about 8 µJy/beam. RSN rate will be and the physical setting for OHMs. The (Courtesy: Colin Lonsdale) possible. Further monitoring on one of the proposed severely sensitivity-limited, allowing data processing OHMs, IRAS 02524+2046, was com- only modest spectral resolution on the will reveal many more details about the pleted in January 2003 (see Fig. 16). masers, and probing only the peak of maser emission. For example, weak Extra time was requested on this object the RSN luminosity function. Nearly all maser amplification along lines of sight to study the daily fluctuations seen in the RSN were found in the westernmost to the 30 RSN candidates will constitute many line components. Jeremy hopes to of the two nuclei in Arp 220, and only a valuable probe of detailed properties in find signatures of delays in the data which 2 very faint candidates were seen in the regions inaccessible to other techniques would be indicative of angular separa- eastern nucleus. because of opacity and lack of resolution. tions between masing components and Future VLBI observations with Arecibo provide a crude geometrical picture of In Nov 2002, a new VLBI experiment may have the sensitivity to observe these the masing. However, this will depend on was conducted by Colin Lonsdale (Hay- phenomena in other IR galaxies. good models of interstellar scintillation. stack), Carol Lonsdale (IPAC), Gene Smith (UCSD) & (Jodrell) which included several large European The Variability of OH Megamasers The Magnetic Field in a Damped dishes, the VLBA, the phased-VLA, the Jeremy Darling (Carnegie) has under- Lyman-Alpha Absorber GBT, and Arecibo. When combined with taken, (1) a long-term monitoring pro- Wendy Lane (NRL) & Carl Heiles almost continuous recording at a rate of gram of four OH megamasers (OHMs), (Berkeley) have attempted to measure 256 Mbit/sec, this experiment is probably and (2) a program to characterize short- the magnetic field in the z=0.0912 HI the most sensitive VLBI observation to term variability of two OHMs with strong 21cm/Damped Lyman-alpha absorption date. A preliminary continuum image, emission lines (the time-scales sampled system towards the quasar B0738+313 Fig. 15, boasts a rms noise level of only via Zeeman splitting. This system is IRAS 02524+2046: 23 day mean and rms spectrum 8 µJy/beam, and this can be reduced by one of the strongest known redshifted further processing to perhaps as low 0.01 21-cm absorbers visible from Arecibo, as 6 µJy/beam. The more than 3-fold making it an ideal candidate for this experiment. Preliminary results

improvement in SNR afforded by Are- 3 − sys 10 T cibo, the GBT and a wider recording × indicate that the upper limit on the 5 bandwidth has resulted in the detection of % strength of the line-of-sight magnetic roughly 30 RSN candidates in Arp 220, field is ||B = 2 ± 2.25 µG. This is con- about 10 of which are found in the eastern RMS Spectrum sistent with measurements made in nucleus. The brightest source in the field HI clouds in our Galaxy. As Zeeman 0 of view is slightly below 1 mJy. 1000 1200 1400 1600 1800 2000 splitting is not sensitive to magnetic Channel fields oriented perpendicular to the This preliminary image constitutes Figure 16: The average and rms OH spectrum of IRAS line of sight, no conclusions can be 02524+2046. The bandpass is 6.25 MHz (6 kHz or 1.3 kms−1 dramatic evidence that intense star for- drawn about the total magnetic field per channel). The average spectrum is of 23 nearly consecu- mation is occurring in both nuclei, and in this system. not just the western one. It is of particular tive daily observations and the rms spectrum within those 23 observations indicates several variable components. The importance to deduce the supernova rate rms spectrum has been offset and scaled for comparison to in luminous IR galaxies as a measure of the average spectrum. (Courtesy: Jeremy Darling)

June 2003, Number 36 14 NAIC/AO Newsletter June 2003, Number 36 15 NAIC/AO Newsletter 3C258 lobes separated by only about 380 but failed to find OH lines associated pc. Assuming a spin temperature with AGN in quiescent (non-interacting) 0.08 of T (K), and a covering factor of systems, placing stringent limits on the unity, the total neutral-hydrogen influence of AGN in forming OHMs in 0.06 column density is about 4.5 × 1018 non-interacting galaxies. T cm−2. Six Gaussian components 0.04 with rather narrow velocity widths Fractional Absorption A Search for Low Mass HI Clouds in 0.02 (half-height widths between ~4 and 10 kms−1) fit the feature well the Local Hubble Volume

0.00 (Fig. 17). Compared to other Riccardo Giovanelli, Kristine Spekkens, 4.945×10 4 4.950×10 4 4.955×10 4 4.960×10 4 known CSS HI-absorption spec- Chris Springob, Karen Masters, Barbara Heliocentric Velocity (Km/s) Figure 17: The HI absorption spectrum of 3C258 expressed tra, 3C258 contains probably the Catinella & Martha Haynes (Cornell) as fractional absorption vs , where fractional most complex absorption system, have begun a spectral line mapping

absorption = (Scont – S(ν))/Scont, Scont being the “unabsorbed” with the fitted components having program designed to detect HI clouds continuum flux density of the source. The dotted lines show 6.5 about an order of magnitude nar- down to a mass limit of 10 M8 in the 6 Gaussian components fitted to the spectrum, while the rower velocity widths than most the very local universe. While the main crosses mark the residuals after these are subtracted from the objective of this program is to probe the spectrum. (Courtesy: Tapasi Ghosh) features in other CSS sources (e.g. Vermeulen et al., Astro- faint end of the HI mass function, it will Detection of HI Absorption in 3C258 Ph/0304291). Although detailed also allow a comparison of the quality of Compact Steep Spectrum (CSS) radio modeling of the HI gas seen in absorption baselines derived from drift-scan and on- sources are a subclass of FRII radio in this galaxy will require VLBI imaging the-fly (OTF) mapping, a question with sources having both linear sizes of less of the line and continuum emission, it is significant ramifications for future ALFA than 20 kpc and steep high frequency difficult to imagine that a single rotating extragalactic HI survey strategies. Fur- radio spectra. Observational evidence disk/torus would produce such a complex thermore, this pilot project will be useful implies that these objects are young, and absorption system. It may be that jet- in developing software and analysis tools asymmetrically distributed gas is found ISM interactions play the dominant role necessary to tackle the massive amounts close to their nuclei. In a search for HI in shaping the structure/properties of the of data that will be produced by ALFA absorption and OH emission or absorp- object. In fact, the signature of distur- projects. The first 100 hr of observa- tion against a sample of 16 CSS and other bance is perhaps already evident in its tions were made in Jan and Apr, 2003. radio sources, S. Jeyakumar (U. Koeln, optical image. The HST image of 3C258 This allocation amounts to one third of Germany), D.J. Saikia (NCRA, India), (Fig. 18, reproduced from De Vries et al., the time that simulations predict will be Chris Salter, Tapasi Ghosh (NAIC) & 1997, ApJS, 110, 191) displays arc-like Juergen Stutzki (U. Koeln, Germany) structure of high surface bright- have found a complex, multi-component ness, with a larger, fainter tail HI absorption system towards 3C258. extending to the northeast, roughly

perpendicular to the bright central 34.0 The CSS radio galaxy, 3C258, lies arc. The overlaid radio continuum at a redshift of 0.165, and has two radio image (5-GHz MERLIN; Akujor 33.5 et al., 1991, MNRAS, 250, 215)

is at right angles to the central dec [deg]

59˝ region and contains the entire 33.0 VLBI double-lobe structure (Sanghera et al. 1995, A&A, 58˝ 32.5 295, p. 629). 8.75 8.80 8.85 8.90

57˝ Neither OH absorption ra [hrs] Figure 19: The continuum emission (over a 10-MHz band from Dec (1950.0) nor OH mega-maser emission 1415–1425 MHz) of a region of the sky in the vicinity of the is detected against 3C258 or nearby (7.6 Mpc) galaxy NGC 2683. The axes are R.A. (hr), 19°35´56˝ any other of the radio sources and Dec (deg). Each horizontal strip is normalized to the aver- observed. This is of interest age flux in that strip, leading to the spurious horizontal stripes. 11h22m6s.50 6s.45 6s.40 6s.35 6s.30 6s.25 6s.20 given the conclusions of Darling The map was obtained in OTF mode with a R.A. drive rate of R.A. (1950.0) & Giovanelli (NAIC Newsletter, 6 sec/beam (twice the drift rate) and spaced in Dec each 1.65 Figure 18: The HST image of 3C258 from De Vries et al. No. 31) who searched for OH arcmin (Nyquist sampling). The map covers 2° × 1.5° (265 × 200 (1997, ApJS, 110, 191). Overlaid is the MERLIN 5-GHz megamasers in nearby AGN kpc at a distance of 7.6 Mpc) and required 10 hr of telescope radio continuum map of Akujor et al. (1991). (Courtesy: time spaced over 5 days. Further data processing is on-going. which are undetected by IRAS, Tapasi Ghosh) (Courtesy: Martha Haynes)

June 2003, Number 36 14 NAIC/AO Newsletter June 2003, Number 36 15 NAIC/AO Newsletter needed to derive a statistically meaning- held at Arecibo in March (see: http: 4 ful result. //alfa.naic.edu/extragal/meeting1/ minutes/ALFALFAsprouts.html). 3 CDM numerical simulations predict the existence of large numbers of low- These observations represent just 2 mass halos, well in excess of the faint tail the first step in a larger HI mapping 1 of the galaxy luminosity function. This project, with more surveys planned for 0 prediction has prompted the reevalu- use with ALFA, with the goal of achiev- Flux Density (mJy) ation of the idea that some, relatively ing survey coverage across the entire −1 compact, high velocity HI clouds may Arecibo sky. On-going work involves be the “missing” population of low-mass experimentation with the best methods 2×104 2.1×104 2.2×104 V (km/s) halos in the Local Group. Large blind to perform bandpass calibration and HEL Figure 20: HI profile for AGC 241061, the fastest rota- HI surveys (with few systems detected subtraction, continuum cleaning, beam tor in the sample. The dashed lines correspond to the 8 with MHI < 10 M8, and almost none characterization and deconvolution, velocity range used to display the Hα rotation curve in 7 with MHI < 10 M8 ) disagree by an noise characterization, and HI signal Fig. 21. (Courtesy: Barbara Catinella) order of magnitude in the estimate of detection and extraction. the space density of objects with masses At low z, rotational widths are usu- 7 ally derived either from HI line profiles of MHI ~ 10 M8. The current survey aims at resolving this discrepancy. Calibration of the SDSS Spectroscopic or via optical Hα rotation curves. At Line Width Scaling Relations higher z, long-slit/IFU spectroscopy The program takes advantage of the Determination of the rotational param- currently exists for only a few dozen fact that the ratio of low-mass to high- eters of disk galaxies is of crucial impor- objects. In contrast, the large on-going mass halos in numerical simulations tance for several areas of observational Sloan Digital Sky Survey (SDSS) prom- appears to be the same in high and low cosmology, ranging from galactic struc- ises to deliver, over the next few years, density regions. Square-degree sized ture and dynamics, to galaxy formation a million galaxy spectra from which fields are mapped, centered on known and evolution across cosmic time. In linewidths can be derived. The main galaxy groups for which primary distance particular, scaling relations such as the obstacle to applying the copious SDSS indicators give distances of 3–10 Mpc. Tully-Fisher (TF) relation are used to linewidths for comparison with similar Maps of this size will inevitably include a determine the extragalactic distance scaling relations at low z arises from the large number of continuum sources (as is scale, map the large-scale velocity and need for common calibration of the width seen in the map of the NGC 2683 region mass distribution, and constrain N-body measures obtained using fundamentally shown in Fig. 19), which provide a chal- simulations of cosmological scenarios. different techniques and over the larg- lenge in the data reduction process. The latter suggest that disk scaling est possible redshift range. The SDSS fiber diameter limits the spatial scale The observing mode varies as a func- relations should change as galaxies over which the linewidth is measured, tion of the target group’s distance. The evolve. For example, even at modest so that its measures are most applicable more distant groups required 12 s (or redshifts (z ~ 0.4), it is suggested that at intermediate to high z. Since the most more) integration per beam to achieve the co-moving star formation rate is prominent Hα line can be traced only up the required HI mass limit. Therefore, higher than today so that, for a given to z < 0.4, application of the method to observations of those areas were made gravitational potential, the associated higher z will require use of linewidths in drift-scan mode. Nearer groups were luminosity may be higher by a factor from other species such as [OII]λ3727Å observed using OTF mapping, with a of 3. It is thus important to ascertain and [OIII]λ5007Å. It is therefore impor- slew rate set such as to reach the mass the scale within which a relation such limit (3 s per beam in the fastest case). as TF yields cosmologically unbiased Preliminary results suggest that short results and to determine how the mass- 2.16×104 to-light ratio M/L varies with lookback integration time OTF mapping, in which 2.14×104 the telescope is driven at a rate of up to time, a diagnostic of galaxy evolution. ) half the maximum slew speed, results in Several recent studies based on optical 2.12×104

spectroscopy reveal an intriguing state (km/s data quality that is indistinguishable from 4 HEL 2.1×10 data taken in drift-scan mode. That is, of conflict in this field. Results vary V the channel-to-channel rms is the same between the inference that, even at 2.08×104 in both cases, and no long period oscil- modest redshifts, M/L is substantially 2.06×104 lations are introduced by the fast slew different (in excess of a magnitude) -10 0 10 rate. Preliminary quantitative results from that at z=0, to ones that infer no R (arcsec) were presented by Kristine Spekkens significant change out toz ~ 1. Figure 21: Combined Hα + [NII] long-slit rotation profile (outer and central points, respectively) for AGC 241061. at the Extragalactic ALFA workshop (Courtesy: Barbara Catinella)

June 2003, Number 36 16 NAIC/AO Newsletter June 2003, Number 36 17 NAIC/AO Newsletter Jeff Gardner (U. Pitt), Barbara Catinella, HI line width of 786 kms−1, and that Martha Haynes, Riccardo Giovanelli which required the longest integration (Cornell) and Andy Connolly (U. Pitt) time (250 min). Figs. 21 & 22 show observed the HI emission from a sample the corresponding Hα rotation curve of galaxies with 0.04 < z < 0.09 that are (obtained at Palomar) and the I-band included in the SDSS spectroscopic image (obtained at Kitt Peak). survey and for which optical long-slit spectra have already been obtained with the Palomar 5-m telescope. A detection Local Group Studies rate of 85% was achieved; use of the radar Tim Robishaw, Josh Simon & Leo Blitz blanker proved critical to avoid RFI from (Berkeley) used two observing runs in the FAA radars. Total integration times the second half of 2002 to continue their between 25 and 250 min were required in Arecibo investigation of an apparently order to achieve an average rms noise of interacting system that consists of a high- Figure 22: False color, I-band image of AGC 241061. about 0.3 mJy and peak signal-to-noise velocity cloud (HVC) and a Local Group The major diameter of this Sb spiral is ~0.6 arcmin. ratio >6, depending on the HI content dwarf galaxy. The HVC was discovered (Courtesy: Barbara Catinella) and profile width. Widths have now been by Robishaw, Simon & Blitz (ApJ, 2002, extracted and a comparison is being made 580, p. L129) during their survey of Local tant to establish a cross calibration of of the linewidths measured by different Group dwarfs observable with Arecibo. the TF relation by comparing linewidths tracers/techniques and with the results Due to the faint HI tails that they saw measured using different kinematic trac- of simulations of the instrumental limi- extending away from the main body of ers for a single set of galaxies to as large tations. The cross calibration of the opti- the HVC, and the proximity of the HVC redshifts as possible, typically beyond the cal and radio TF relations constitutes a to the Local Group dwarf spheroidal distances included in previous Arecibo major part of Barbara Catinella’s Ph.D. galaxy LGS 3, they proposed that the peculiar velocity studies. research at Cornell. two objects were interacting tidally. Specifically to explore the cross Already unique because of this possible Fig. 20 shows the HI profile for the interaction (implying a distance of ~700 calibration of the HI, long-slit Hα and galaxy AGC 241061, the fastest rotator in SDSS linewidth relations, in Mar 2003, kpc to the HVC), the HVC was rendered the target sample, showing an observed even more intriguing by the finding that it contains a smooth velocity field indica- −1 −1 vLSR [km s ] tive of rotation: the HVC has a 16 kms ]

1 346 340 334 327 321

− gradient along its major axis. The rotation 11.8 curve of the HVC shows that it is dark 5.9 matter dominated, with 80% of its mass

v [K km s in dark matter if it is located at 700 kpc; 0.0

∑Τ∆ the ratio of total-to-HI mass gets larger

10' if its distance gets closer. +22°00' The first new data set acquired by 50' Tim, Josh & Leo consists of an on-the-fly

map covering a similar area to the pub- 40' lished one, but with much more integra- 30' tion time and a corresponding increase in 20' sensitivity. They also made the new map about 30´ wider to facilitate the use of

DECLINATION (J2000) 10' their standing-wave removal routine (see +21°00' Robishaw et al. 2002, or NAIC News- letter No. 33). This map, displayed in 01h 11m 10m 09m 08m 07m 06m 05m 04m 03m 02m 01h 01m RIGHT ASCENSION (J2000) Fig. 23, shows the tidal tails much more Figure 23: High-resolution HI map of an HVC and LGS 3. This color-intensity (velocity-column density) image clearly than the original lower sensitiv- consists of ~30 hr of on-source integration time acquired over the course of 8 nights. The pixel size is 1.5´, or ity data. The tails can now be seen as slightly less than half of a beamwidth. Visible in the map are the Local Group dwarf galaxy LGS 3 (the bright spatially continuous structures, and their red object at (α,δ) = (01h03m54s, +21° 53´) in the upper right), a compact HVC (the large double-lobed 2000 connection to the main body of the HVC -1 cloud centered slightly above the middle of the map) with a 16 kms gradient across it, and two long HI tails is obvious. One feature of the tails that extending to the southeast and southwest of the HVC) that are argued to be remnants of a tidal interaction between LGS 3 and the HVC. Compare to Fig. 1 in Robishaw et al. (2002). (Courtesy: Tim Robishaw) will certainly receive further study is

June 2003, Number 36 16 NAIC/AO Newsletter June 2003, Number 36 17 NAIC/AO Newsletter 1 vLSR [km s ] ISM of IC 1613, high surface brightness galaxies which ]

1 242 239 236 233 230 − 351 including a undergo dramatic evolution. They are bright cloud not necessarily related to the more com- 176 v[K km s (T = 18 K!) monly known Blue Compact Dwarfs. At 0 A ∑Τ∆ east of center z~1, LCBGs have a total star formation +02°30' and two HI rate equal to that of grand design spirals, holes near the but their number density is decreased by center. The very an order of magnitude by z~0. It is not 20' low-amplitude known what drives their rapid evolution, rotation of this nor what is their final state. galaxy is also 10' To date D.J. and collaborators have visible in their obtained HI spectra for 14 nearby LCBGs data. This is the selected from the Sloan Sky Survey using +02°00' first Nyquist- Arecibo in service observing mode. The

DECLINATION (J2000) sampled single- observations were conducted by Héctor dish map of 50' Hernández (NAIC), and were of very IC 1613. They high quality. Based on a preliminary plan to use the analysis of these galaxies and others data from the 9 40' observed with the GBT, nearby LCBGs dwarfs to study 01h06m 05m 04m 01h03m are HI-rich, with masses ranging from RIGHT ASCENSION (J2000) the radial pro- 5×108 to 9×109 M , and have large Figure 24: HI map of the Local Group dwarf irregular galaxy IC 1613. This color- files of veloc- 8 intensity (velocity-column density) image was made with a single ~1.5 hr on-the-fly dynamical masses, ranging from 5 109 ity dispersion × map. The pixel size is 1.5´, or slightly less than half of a beamwidth. The dwarf to 2×1011 M . Using IRAS fluxes to and HI column 8 galaxy is easily resolved by Arecibo, and the small but regular velocity gradient is determine star formation rates, they find density in dwarf clear. (Courtesy: Josh Simon) that their sample has gas depletion time galaxies. The scales ranging from 5 108 to 1010 yr. their apparently discontinuous velocity HI distribu- × These properties imply that while LCBGs field. These observers recently made a tions at low column densities can be are a diverse collection of galaxies, they VLA mosaic of the HVC and LGS 3 that compared to the predictions of current tend to be high mass objects which have they will combine with the Arecibo map theories about the behavior of neutral gas the potential for future bursts of star to increase the angular resolution by a when subjected to the metagalactic UV formation. They will be observing more factor of four. With the high-sensitiv- radiation field (e.g., Sternberg, McKee LCBGs at Arecibo in the coming year ity, high-resolution combined map, they & Wolfire, 2002, ApJS, 143, p. 419), yielding data on all 70 LCBGs within will test the tidal interaction hypothesis while the velocity dispersions of gas in 200 Mpc. by comparing it with theoretical models. the outer parts of dwarfs can be used to This, they hope, will elucidate the his- test the hypothesis that dwarf galaxies tory of the system and provide further have much larger dark matter halos than The Effect of the Cluster Environment constraints on the structure of the HVC. previously realized (Stoehr et al., 2002, on Galaxy Evolution in the Pegasus I For the second set of new observa- MNRAS, 335, p. L84; Hayashi et al., Cluster 2003, ApJ, 584, p. 541). tions, Tim, Josh & Leo mapped out a Understanding the rapid evolution of much larger area (4° × 6°) centered on the star formation rate in rich clusters of the HVC in order to check whether this An HI Survey of Nearby Luminous galaxies since z=0.5, first documented region contained any other unknown HI Compact Blue Galaxies by Butcher & Oemler (1978, ApJ, 219, clouds. They verified that the HVC and p. 18; 1984, ApJ, 285,p. 426), remains a Recently, D.J. Pisano (ATNF), Catherine LGS 3 are the only HI-rich objects within central issue in extragalactic astronomy. Garland, Jonathan Williams (Hawaii), several degrees; however, they also dis- Subsequent spectroscopy and HST imag- Rafael Guzman (Florida), & Francisco- covered that the western tail of the HVC ing has revealed a higher fraction of spiral Javier Castander (IEEC-Barcelona) extends much further to the southwest galaxies in distant clusters than in present began a study of the HI content and than had been revealed by their previ- clusters (Dressler & Gunn, 1983, kinematics of nearby Luminous Com- ous maps. ApJ, 270, p. 7; Dressler et al., ApJS, pact Blue Galaxies (LCBGs) as part 122, p. 51). The heart of the problem, They also mapped their ninth Local of a larger multiwavelength campaign then, is to explain the rapid evolution in Group dwarf galaxy, the dwarf irregular to better understand their more distant the spiral population since z=0.5 and, in IC 1613. This new map (Fig. 24) shows analogs. LCBGs at intermediate red- particular, how they can be so effectively some of the small-scale structure in the shifts are blue, vigorously star-forming,

June 2003, Number 36 18 NAIC/AO Newsletter June 2003, Number 36 19 NAIC/AO Newsletter h Virgo cluster, while at i.e., optical angular diameters, apparent 2 the same time a vir- blue magnitudes, and morphological 12000 tually undetectable types, now represent the principal error level of X-ray emis- in diagnosing HI depletion in the Pegasus h 1 sion, and very low spirals. With their new HI observations, velocity dispersion. in conjunction with better blue magni- 8000 The low velocity dis- tudes than were available for previous persion, coupled with studies, they conclude that there is no

h the lack of a dense hot sign of overall HI deficiency for spirals in 24 4000 ICM, indicates that the Pegasus I cluster. Although there may ram pressure strip- be isolated cases of individual galaxies in ping should not play Pegasus I with a smaller HI content than a significant role in expected for their size and morphological 0 this environment. type, these are clearly the exception and 23h Nevertheless, impor- not the norm in the cluster. cz (km/s) tant environmental Figure 25: The z distribution out to cz=15000 kms-1 of “blue edge” galaxies effects are taking within the Pisces-Perseus field. (Courtesy: Juan Cabanela) place in the cluster, “Blue Edge” Galaxies in the Pisces- transformed into S0 galaxies in present as a number of early- Perseus Field epoch clusters. It has long been evident type galaxies exhibit evidence for recent, Juan Cabanela & Megan Roscioli that the cluster environment is capable of centrally concentrated, star formation. (Haverford) have made HI observa- removing the gas from a galaxy via ram Thus Pegasus I provides an unusual tions to acquire a large enough sample pressure stripping (Gunn & Gott, 1972, situation in which to isolate the effects of “blue edge” galaxies in the Pisces- ApJ, 176, p. 1). However, several tidal of tidal perturbation on the evolution of Perseus supercluster (PPS) region to perturbation scenarios have also been its galaxies, unless tidal stripping is more map out their distribution relative to suggested that could drastically deplete effective in low velocity dispersion envi- the large-scale structure of the PPS. the ISM in spiral galaxies by inducing ronments than previously considered. The scientific goal is to obtain a better large episodes of star formation (Moore understanding of the environments that It has recently been shown, contrary et al., 1996, Nature, 379, 613; Bekki, host Low Surface Brightness (LSB) gal- to previous studies (Bothun, Schommer, 1999, ApJ, 510, p. L15). axies and, as established in Cabanela & & Sullivan, 1982, AJ, 87, p. 725), that Dickey (2002, AJ, 124, p. 78), the “blue While the most dramatic evidence for at least some spirals in Pegasus I have a edge” galaxies (named for their location evolution in cluster galaxies is seen at deficiency in HI content (Solanes et al., in a POSS I color-magnitude diagram) higher z, several studies have revealed a 2001, ApJ, 548, p. 97). This has very appear to be LSB galaxies as well. An surprising amount of similar evolution- important implications with regard to the examination of the z distribution of the ary processes ongoing in nearby clusters, evolution of cluster galaxies, i.e., ram 19 “blue edge” galaxies detected by albeit at a reduced level (Caldwell et al., pressure sweeping may play a signifi- Cabanela & Dickey revealed that these 1993, AJ, 106, p. 473; Caldwell & Rose, cant role in galaxy evolution in a wider have a very similar redshift-space dis- AJ, 113, p. 492). Recently, Lorenza Levy variety of environments that previously tribution to those “normal” high surface & Jim Rose (UNC) have been approach- considered. Lorenza & Jim’s main goal is brightness galaxies already cataloged in ing the important issue of what trans- to clarify the conflicting claims regarding the PPS field. Based on this finding, Juan forms spirals into S0’s by concentrating whether there is HI depletion in spirals in & Megan were awarded Arecibo observ- on nearby clusters, where the increased the Pegasus cluster. Resolving this issue ing time to make HI observations of over spatial resolution and S/N ratio allows is fundamental to determining whether 150 “blue edge” galaxies in the Pisces- far more diagnostic information to be ram pressure stripping is effective in a Perseus field in the hope of building up a extracted regarding the relative roles of wider variety of cluster environments catalog of LSBs there. The observations gas removal mechanisms. than previously thought. were completed over 9 nights in Sept Their study has focused on obtaining With the above goal in mind, they & Nov 2002. From 150 targets, they HI observations of the Pegasus I cluster have acquired new 21-cm observations detected some 86 of their “blue edge” for the purpose of identifying the cluster of 48 spiral galaxies in the Pegasus I galaxies in HI, meaning that they now mechanism responsible for the observed cluster, with the improved sensitivity of have identified over 100 likely LSBs in evolution. The Pegasus cluster represents the Gregorian feed system. Uncertainties the field of a single supercluster. a unique environment, of particular inter- in the HI fluxes have now been reduced An initial result from a “by eye” est because it has a richness similar to the to the point where other uncertainties, examination of the z distribution of their

June 2003, Number 36 18 NAIC/AO Newsletter June 2003, Number 36 19 NAIC/AO Newsletter “blue edge” galaxies is seen in Fig. 25. This is a redshift slice out to cz=15000 kms−1 for their field. The previously cataloged ZCAT galaxies are green dots and Juan & Megan’s LSB candidates are red stars. It is clear that the LSBs trace out the same large scale structures as the “normal” high surface brightness galax- ies. They are now working on a more quantitative analysis of the z distribution of these LSB candidates within the field, and also combining their new LSB cata- log with the extensive HI observations of Giovanelli, Haynes & collaborators of “normal” galaxies in the PPS field to allow a clearer determination of the trends of surface brightness and HI con- Figure 1: The image on the left is a Mercator map of the degree of linear polarization associated with the crater tent versus environmental density than Nelike, which has been combined with a Magellan SAR image. The original SAR image is shown on the right has been previously possible. for comparison. The image is 678 km by 773 km. Red areas have the highest fraction of linearly polarized echo (18 %), while darker blue areas have a very low fraction (< 1 %). Nelike is 6.1 km in diameter, which makes it one of the smallest craters with a parabolic deposit. (Courtesy: Lynn Carter). with Arecibo, so there was little inter- scattering of the incident wave. Tor Hag- Solar System Studies est in Arecibo radar observations of fors, a former NAIC Director, pioneered Don Campbell, Mike Nolan, and Ellen the planet over the following decade. this technique in the 1960s for studies Howell However, the Magellan radar was a of the lunar regolith and it was greatly single polarization radar transmitting refined by former Cornell graduate stu- and receiving horizontal linear polariza- dent Nick Stacy for further studies of the Venus revisited: tion and could not study the polarization Lunar surface. he exploration of the surface of Venus properties of the reflected signal. These The greatly improved post upgrade under the planet’s thick cloud cover properties are sensitive to the presence of T sensitivity of the Arecibo S-band radar was one of the telescope’s prime objec- thin deposits on the surface and provide system made such measurements possi- tives during the early years of Arecibo some information about their electrical ble for Venus. From observations in 1999 and was a major motivation for NASA properties. A fraction of the radar wave and 2001 Cornell graduate student Lynn providing the funds for a high powered is reflected from the atmosphere-surface Carter has made images of the surface S-band radar transmitter during the first interface with the remainder transmitted of Venus in all four polarization Stokes’ upgrade of the telescope in the 1970s. into the surface where it is normally parameters and mapped the degree of Arecibo observations of Venus through absorbed. However, in the case of a thin linear polarization over the surface. the mid-1980s made the first images of (no more than a few wavelengths) surface There are a surprising number of features the planets surface with sufficient resolu- layer overlying a higher refractive index in the maps strongly correlated with such tion that different terrain types could be subsurface the transmitted wave will be terrain features as impact crater haloes, clearly recognized. Impact crater counts reflected from the underlying subsurface volcanic dome fields, and wind blown derived from these images provided the through the surface layer and contribute to deposits indicating that significant areas first solid evidence that the surface of the radar echo power. For a purely circu- of the surface of Venus are covered by Venus was quite young with an average larly polarized incident wave, which has thin deposits of, probably, fine grained age of less than one billion years. In the equal amplitudes in any two orthogonal material. This means that the surface of years just prior to the Magellan mission linear polarizations, the reflected wave Venus may look surprisingly different in to Venus, the Arecibo imagery was one will be partly linear polarized since, for a visible wavelength images than it does at of the main resources for studies of the smooth atmosphere-surface interface, the the 13 cm wavelength of the Magellan planet’s surface. reflection and transmission coefficients radar due to the penetration of the radar depend on the orientation of the linear wave into the surface. Figure 1 shows With resolutions of 150 m to 250 m polarization relative to the plane of inci- the Arecibo degree of linear polarization Magellan synthetic aperture radar (SAR) dence. Hence, the presence of linearly image and the Magellan radar image of images of the surface of Venus obtained polarized power in the reflected echo is a region around the small 6 km diameter in the early 1990s have about ten times indicative of penetration and subsurface better resolution than can be obtained crater Nelike.

June 2003, Number 36 20 NAIC/AO Newsletter June 2003, Number 36 21 NAIC/AO Newsletter Updates on the Observ- ing Program Asteroid 2002 NY40 passed within 0.0035 AU of the (1.4 times the distance of the moon) on August 18 and was observed at a number of optical/infrared tele- scopes and radar systems, includ- ing the Arecibo 12.6-cm radar. Due Figure 4: This image shows a times-series of images of asteroid to the very short round-trip-light (5381) Sekhmet. Distance from the observer increases towards travel time, (as low as 3.8 seconds) the bottom, and velocity towards the observer increases towards we performed a bi-static observa- the right. In each of the four frames, the primary is near the tion with reception of the radar top, and the secondary can be seen moving towards the top echo at both Arecibo (when pos- of the image. The image is about 2 km from top to bottom. Figure 2: A 70-cm wavelength Arecibo view of the (Courtesy: Mike Nolan) lunar crater Aristarchus (42 km diameter) and the sible) and the 100-m Greenbank adjacent Aristarchus Plateau. The Plateau is covered Telescope (GBT) of the National this rotation rate, the observed bandwidth to a depth of several meters by fine-grained volcanic Radio Astronomy Observatory. A series requires a linear extent of 610-m. It is ash, which appears dark to the radar. The bright arc of range-Doppler images taken of this likely that on this date the viewing geom- that begins just west of Aristarchus is a lava-carved object is shown in Figure 3. The part etry was near the equator so that the true channel. Early eruptions of very gas-laden magma of the asteroid closest to the earth is extent of the asteroid is close to 600 m. from the head of this valley created much of the dark at the top of the images with distance This then gives an average optical albedo mantling layer. These new 70-cm observations permit (reflectivity) of 0.17 ± 0.03, using the H identification of additional source vents across the along the line-of-sight from the earth Plateau, and may allow estimation of the deposit (range) increasing from top to bottom, magnitude of 19.669 ± 0.128 determined depth. (Courtesy: Bruce Campbell — NASM). and Doppler frequency increasing to the by M. Hicks from photometry at Table right. The overall appearance is that of Mountain Observatory. A Lunar excursion: two lobes joined together, similar to other Bruce Campbell (National Air and Space Ellen Howell (NAIC) and collabora- apparent ‘contact binaries’ that have been tors also obtained near-Infrared spectra Museum) and collaborators are scheduled observed. On August 18 the two lobes are to perform 70 cm radar observations of of this asteroid using the NASA Infra- at roughly the same range, and we esti- red Telescope Facility in Hawaii. The the Moon in June aimed at imaging the mate the range depth of 22 and 16 image south polar region and other areas. This medium resolution spectrometer, SpeX, pixels implying 165 and 120 meters radii was used to measure the reflectance relatively long wavelength is being used for the left and right lobes respectively. in order to penetrate the maximum dis- spectrum from 0.8 to 2.5 microns. They If the lobes are roughly spherical, the also observed in the 2.6 to 3.5 micron tance into the lunar surface to search for long axis is then at least 570 meters. subsurface ice deposits at the south pole region, which has a significant thermal The observed Doppler bandwidth, component longwards of 3.0 microns and to possibly penetrate the full depth of which indicates the projected rotation the regolith in other areas. Results from for objects near 1 AU. The reflectance velocity in the line of sight, was largest spectrum is a remarkably good match earlier Arecibo observations by the same on August 16 at 0.84 Hz. The rotation group are shown in Figure 2. to LL6 ordinary chondrites. Thermal rate of 2002 NY40 was determined modeling in the 3 micron region gives from optical lightcurves (the variation an estimated albedo of 0.15 – 0.25, which in the amount of reflected sunlight as the is consistent with the value of 0.17 ± 0.03 asteroid rotates) to be 19.99 hours. Using obtained from the radar images. Labo- ratory measurements of LL6 ordinary chondrites show albedos closer to 0.2, but with a wide range of values within a single meteorite. It is unusual to find asteroid and meteorite spectra that match this closely. This may be in part because it is rare that Figure 3: These images of near-Earth asteroid 2002 NY40 were taken (left to right) on August 16, 18, 19 and near-Earth are as well observed 20, 2002. In each, the range increases top to bottom and projected velocity (Doppler) towards the observer as 2002 NY40, with shape estimates from increases to the right. The image on August 16 was received at Arecibo. Reception was with the GBT for the the radar observations and high-qual- other dates. The resolution is 15-m per pixel in range on August 16, and 7.5-m per pixel for the other dates. The object looks remarkably like two balls joined together. (Courtesy: Ellen Howell)

June 2003, Number 36 20 NAIC/AO Newsletter June 2003, Number 36 21 NAIC/AO Newsletter ity visible and infrared spectra being Personnel: with the Visitor Center and its teacher obtained. Tony Crespo retired at the end of April training workshops. The asteroid 4 Vesta has an enig- (see “comings and goings”), after many The students worked on individual matic surface. It is the second largest in years of keeping the S-Band transmitter research projects in radar and radio the . It cannot be extremely operational under often adverse condi- astronomy, atmospheric science and heavily cratered, as its surface is chemi- tions, regularly repairing the transmitter computing with their advisors. cally the crust of a differentiated object, during the day so that he could operate it In addition to a large number of which would be removed by heavy cra- at night. Everyone in the planetary radar summer student talks by the observa- tering. Yet many meteorites (the “HED” community is greatly in his debt. Víctor tory staff and visiting scientists, the stu- achondrites) and small asteroids (the Negrón continues day-to-day operation dents also had the opportunity to work “chips off Vesta” discovered by Richard and maintenance of the transmitter. A on several specially designed hands-on Binzel and collaborators) appear to have search for an engineer for all of the Are- observing projects. Mike Nicolls (Cornell been delivered to Earth as the result of cibo transmitters is underway. University), who was a summer student a very large impact event, leading to the at the Observatory in 2001, returned for hypothesis that a large crater could be three weeks to continue research with found on the surface. Colors and shape Sixto González and Néstor Aponte. determined from HST imaging are The 2002 NAIC Arecibo Observatory Mike had a very productive and fruitful consistent with such a crater. Vesta is Summer Program summer, working on technical aspects as also the target of the DAWN spacecraft Ramesh Bhat, Lisa Wray, Qihou Zhou well as science. mission. leven students from colleges and uni- The NSF Research Experience for Radar measurements can measure Eversities in the mainland and Puerto Undergraduates (REU) program spon- shape directly, without confusion by Rico participated in the NAIC Summer sored eight undergraduates and one albedo features. Vesta had its best radar Student Program at the Arecibo Observa- teacher. The NASA Capability Enhance- observing opportunity for the next cen- tory in 2002. The program also included ment program, based at the University tury in April 2003. At that time M. Nolan a local high school science teacher, José of Puerto Rico, sponsored one student, (NAIC) and collaborators obtained delay- Gerena, from Luis Muñoz Marín public Ingrid Plá Rodríguez, who worked with Doppler images of Vesta, which will be school in Barranquitas. He worked with Sixto González and Craig Tepley. In addi- used to improve the shape model, and José Alonso on projects in conjunction tion, a graduate level student, Samantha particularly to look for features related to the probable presence of a large crater In early May, asteroid (5381) Sekhmet was discovered to be a binary system (Figure 4). It was also seen to be rather smaller (< 1 km diameter) than predicted from optical observations (1.7 km), so that it has high optical and radar albedos and a quite rapid rotation rate (about 2.5 hours). This is the seventh binary near earth asteroid that has been discovered with either the Arecibo and/or Goldstone radar systems. Binary asteroids are important because it is possible to determine aster- oid bulk density from the orbital param- eters and object sizes; both of which are directly measured by the radar, but are almost impossible to determine by other ground-based means. The frequency of binary asteroids, and the spin rates of the bodies, provide constraints on near-Earth The 2002 NAIC REU summer students, from left to right; Front: Rebecca Wilcox, Martha Boyer, Samantha asteroid formation and delivery. Stevenson, Andrew Helton, and Daniel Kao; Back: Stephanie Morris, Danielle Moser, Laura Chomiuk, Julia Deneva, and Martin Rodgers. (photo by Daniel Kao). Not pictured are Ingrid Plá and José Gerena.

June 2003, Number 36 22 NAIC/AO Newsletter June 2003, Number 36 23 NAIC/AO Newsletter Stevenson (Wesleyan University), was students participated in a 20 hour course tudes in the pulsar magnetosphere than supported by funding from the NAIC. to obtain their SCUBA diving certifica- less intense pulses. The results were tion. presented in a poster paper at the winter The students had many observ- AAS meeting. ing opportunities this summer with Not content with covering the island the 1000-ft Arecibo telescope. All the of Puerto Rico, many scouted out Laura Chomiuk (Wesleyan University) students worked on specially designed neighboring islands including Tortola, studied the connections between super- hands-on observing projects. The topics Culebra, Vieques, Mona, St. John and nova remnant (SNR) G42.8+0.6 and two included pulsar, continuum, spectral-line St. Thomas. angularly nearby neutron stars, SGR and radar astronomy, supervised by the 1900+14 and PSR J1907+0918. This Thanks to the administrative staff of observatory staff (Paulo Friere, Ramesh project employed several radio astronom- the Observatory, the housing situation for Bhat, Tapasi Ghosh, Chris Salter, Karen ical disciplines, including pulsar search this year’s students was very convenient O’Neil, Ellen Howell and Mike Nolan). and polarimetry, HI and OH spectral-line and comfortable. All were housed on- In addition, some students took advan- mapping, and full-Stokes continuum site in the Visiting Scientists Quarters. tage of the opportunity to work with mapping. Laura was jointly supervised They were provided all the necessities Yervant Terzian (Cornell University) by Snezana Stanimirovic (now Berke- plus some luxuries — kitchenettes and and Murray Lewis (NAIC) on a radio ley) and Chris Salter (NAIC), and the computers in each housing unit, and recombination line (RRL) project. Their project also included Dunc Lorimer satellite TV in some units. observations led to successful detections (Jodrell Bank), Ramesh Bhat (NAIC) of several RRLs towards the planetary and Dejan Urosevic (Belgrade) as co- nebulae and supernova remnants. Along 2002 Summer Student Projects: investigators. Several interesting results with the students, Lisa Wray, a receiver have emerged so far, some being quite engineer at the Observatory also took part puzzling. The L- and S-band continuum in the hands-on observing projects. Supported by NSF REU Funds: maps confirm the SNR to possess a well Martha Boyer (University of Minnesota) defined shell showing pronounced edge The projects involved planning and worked on a project that involved studies brightening. The OH 1665/1667-MHz performing the observations, reduc- of pulsar emission regions at multiple fre- data reveal a small-diameter absorption ing and analyzing the data, and giving quencies. Her advisor, Yashwant Gupta patch projected against the SNR interior, short presentations on their experience from National Centre for Radio Astro- at a radial velocity of 18 km/s. The line and findings. Three students had their physics, India, was on a sabbatical visit ratios measured for the 4 OH transitions own observing programs as part of their at the Arecibo Observatory. The work are far from the expected 1:5:9:1 for ther- summer projects. The astronomy students involved development and extension mal equilibrium. An HI feature is also presented the results from their summer of the analysis software for a variety of evident at 18 km/s, closely mimicking research at the winter AAS meeting in statistical studies of the pulse structure the structure of the SNR. Polarimetry Seattle, Washington (see below for more at multiple radio frequencies. on PSR J1907+0918 yields an RM of details). 2 The project employed use of some of 730 rad/m . The OH and HI features Rounding out the technical and the high quality single-pulse data taken have a (far) distance estimate of ~11 ± 3 educational aspect of the summer, the with the Giant Metre-wave Radio Tele- kpc. This is larger than the estimate of students this year showed an admirable scope (GMRT) in India, and also from the ~5.7 kpc for SGR 1900+14, but not adventurous spirit in exploring life out- Effelsberg 100-m telescope in Germany inconsistent with the latest estimate of side the Observatory. Staff-organized and the Lovell 76-m telescope in Jodrell 7.8 (−1.1,+0.9) kpc for the pulsar. Laura trips to local beaches, festivals and Bank, U.K. Martha’s work focused on presented her results in the winter AAS attractions only whetted their appetite. determination of locations of core and meeting in Seattle, WA. They soon took the initiative and guided conal components of pulsars as a function José Gerena, a high school science themselves to almost every corner of the of the pulse intensity and radio frequency. teacher from the Luis Muñoz Marín island. They visited the El Yunque rain Their analysis reveals that for most pul- public school in Barranquitas, was the forest, snorkeled the bioluminescent sars the core component arrives earlier in 2002 Teacher-in-Residence at the Ángel bay in La Parguera — a southern beach, phase for more intense pulses. Ramos Foundation Visitor Center. He visited Luquillo beach on the east side, worked under the supervision of José drove through the famous coffee plan- This shift in phase is seen to be Alonso. The teacher takes part in edu- tations in the central mountain range, larger for lower frequencies (< 1 GHz), cational research projects, and also con- discovered the world-class Ponce Art and nearly disappears at high radio fre- tributes to the outreach activities. In his Museum. Staff member Diego Janches quencies (~5 GHz). These findings are capacity as the resident teacher, Gerena introduced the students to a local diving in support of the hypothesis that more was engaged for most of the summer with instructor, and seven out of the eleven intense pulses originate at higher alti-

June 2003, Number 36 22 NAIC/AO Newsletter June 2003, Number 36 23 NAIC/AO Newsletter the organization of the teacher workshop The receiver configuration was facility at the Observatory. Data are held at the Visitor Center. He designed designed such that measurements of from observations of micrometeor flux several experiments for the CBL Labo- Mie scatter will also be possible, and in the upper atmosphere, conducted in ratory interface that were implemented this will facilitate studies of the rela- January 2002, where three areas of the in the workshop this summer. He also tive sizes and shapes of aerosols in the sky were simultaneously covered, yield- prepared the assessment tools for the atmosphere. Further, when equipped with ing over 20000 events. Danielle’s work workshop evaluation. the appropriate narrow band-pass filters, involved calculation of their line-of- observations of both O and O Raman sight velocities, precise in-atmospheric Andrew Helton (University of Iowa) 2 3 scattering will be feasible with the same decelerations and determination of the worked with Slava Slysh (Astro Space receiver. orbits. The analysis reveals that major- Center of the Lebedev Physical Institute, ity of the detected particles have ellipti- Moscow, Russia) who was on a long sab- Daniel presented his work at the cal orbits, suggesting their confinement batical visit at the Arecibo Observatory. Arecibo Friends Workshop in the 2002 to the solar system. Danielle studied the The project involved all-Stokes survey of CEDAR meeting held in Longmont, orbits of these dust particles, and their OH masers of star forming regions, with Colorado. distribution with respect to the ecliptic the specific goal of searching for possible Stephanie Morris (University of Chicago) plane, based on a/e (semi-major axis vs Zeeman pairs. Andrew worked on data worked on two different projects. Her eccentricity) diagrams. The diagrams for taken with the 1000-ft telescope by his main project, under the guidance of Jeff the north, line and south pointings are advisor prior to his arrival (April 2002) in Hagen, involved development of a web- very dissimilar, and are suggestive of the summer. The observations were made based GUI (Graphical User Interface) for evolution of dust (the meteorides) along with the L-wide receiver with the four tracking and monitoring the pressure and the drag lines. While many particles sub-correlators centered at 1612, 1665, temperature of the compressors used in with a/e combinations along the drag 1667 and 1720 MHz. The observations the telescope’s receiver systems. Hard- lines are seen farthest (north) from the were aimed at refining the positions and ware to collect these data is currently ecliptic plane, eccentricities approach the finding potential sources of Zeeman pairs under construction. The telescope has parabolic limit of unity for those closest for future VLBI follow up observations. recently been outfitted with a new wind to the ecliptic plane. Such an evolution They find eleven possible pairs from the speed monitor, which logs the wind speed was predicted by Morfill and Gruen Arecibo data. Additionally, an OH maser and direction for every second. Stepha- (1979), but was never observed before. was discovered near a known methanol nie developed a GUI for the display This result was presented by Diego in maser 40.2–0.2m, and it was also found and monitoring of these data. The GUI recent ACM conference in Berlin, Ger- to be a source of possible Zeeman pair. could be later extended as a web-based many and its publication is currently in As part of this project, Andrew also tool for the display and monitoring of the preparation. developed IDL-based routines for the compressor parameters. Stephanie also calibration and reduction of all-Stokes Martin Rodgers (Miami University) worked on a pulsar astronomy project, data taken with Arecibo. The results studied the morphologies of sporadic E under the supervision of Ramesh Bhat, were presented as a poster paper at the layers over Arecibo, using the Arecibo where newly discovered pulsars from AAS meeting. data from years 1995–2000 taken by his the Parkes multibeam survey are used to advisor, Qihou Zhou and colleagues. Daniel Kao (Penn State University) study the Galaxy’s magnetic field struc- Martin developed several IDL-based worked with Craig Tepley on a project ture. She adapted and customized the tools to study the statistical nature of the titled “Lidar configuration and observa- software to combine pulsar polarization layers, including layer location, peak tion of Raman scatter from N and H O”. data taken with the WAPP (Wideband 2 2 electron density, layer thickness and The project involved designing and build- Arecibo Pulsar Processor) at different movement of layers. ing of a 3-channel lidar receiver for a Nd: observing days. This will help to improve YAG transmitter to observe Raman scat- upon the quality of polarization results, The results were compared for diur- tering from N2 and H2O. They combined especially for relatively weaker and/or nal, seasonal and solar cycle variances, Rayleigh (at the laser wavelength of 532 less polarized pulsars. The software will and reveal several interesting trends. The nm) and Raman scatter data from N2 (at also allow accurate calibration and cor- main trend is an inverse relation between 607 nm) to extend the lower range of the rection of instrumental polarization, and the occurrence and intensity of E’s to the atmospheric temperature profile down hence will be an important tool for preci- solar cycle; the number and intensity of to 4 km. Observations of Raman scatter sion pulsar polarimetry with Arecibo. layers is lower at solar maximum than from water vapor were made at 660 nm those seen at solar minimum. Another Danielle Moser (University of Illinois, and combined with the N Raman scat- intriguing trend is a maximum of occur- 2 Urbana–Champaign) worked with ter data to derive the water vapor mixing rences in March and minima in both April Diego Janches on interplanetary dust ratio profile from 2.5 to 11 km. and October. At the end of the summer studies using the UHF dual-beam radar

June 2003, Number 36 24 NAIC/AO Newsletter June 2003, Number 36 25 NAIC/AO Newsletter Qihou left the Arecibo Observatory to (Friere et al. 2001) uses the measured part in some of the Lidar experiments take up a faculty position at Miami Uni- pulsar periods and accelerations to deter- with Craig Tepley, and in the Spectral versity in Oxford Ohio. This will give mine these parameters, and works even Line hands-on observing project with ample opportunity for Martin to continue for very sparse data sets. The method is Karen O’Neil. to work on this project with Qihou. They independent of the epochs of individual Samantha Stevenson (Wesleyan) was plan to carry out further detailed research observations. Julia’s work this summer jointly supervised by Tapasi Ghosh and to confirm these trends, and also extend involved its software implementation and Jo Ann Eder. Her research focused on HI the work through analysis of more data testing using simulated data. The new evolution studies of infrared (IR) selected taken over recent years. method works well for data sets of 20 or active galactic nuclei (AGN) galaxies. more period-acceleration measurements Rebecca Wilcox (University of Washing- HI 21-cm spectra were obtained for four (elliptical orbits) or just 4-5 period- ton) worked on Arecibo data obtained 12 micron selected samples: Seyfert 1, acceleration measurements (circular by her advisor, Karen O’Neil (now at Seyfert 2, starburst and nonactive galax- case), and yields fitted parameters that NRAO), over recent years, with the ies. One of the goals was to examine the are close to those used in the simulation. main goal of creating a standard galax- effects of the infrared selection criterion The uncertainties in the fitted parameters ies catalog. The work involved reduction on the infrared evolution characteristics are deduced using Monte Carlo simula- and analysis of the data, comparison with for the galaxies. A comparison of the tion techniques. This method will be par- the published data in the literature, and HI properties of the non-active IR- ticularly useful for weak pulsars where, detailed examination of different kinds selected galaxies with those for an opti- because of interstellar scintillation, posi- of HI profiles. Rebecca also developed cally-selected sample of UGC galaxies tive detections are often few and far apart some IDL-based routines to simplify (Haynes & Roberts 1994) showed no in time. It is also the best possible way the reduction process, which output a significant difference. Another interest- of obtaining first order estimates of the number of parameters including flux ing result is that, while the 12 micron orbital parameters for use in time/period and the velocity width. The analysis sample shows definite global evolution- orbital fitting, even when the sampling is shows several galaxies where the Arecibo ary trends, no difference was noted not sparse. This work was presented in a high-resolution HI profiles do not match between the evolutions of Seyfert 1, 2, poster paper at AAS meeting in Seattle. their previously published descriptions. starburst and non-active galaxies. This Specifically, there are profiles that are Ingrid Plá Rodríguez (University of may indicate that Seyfert 1 and 2 galaxies intermediate between Gaussian (dwarf Puerto Rico – Mayagüez), an Industrial are not in different evolutionary stages (in galaxies) and two-horned (spiral galax- Engineering major, put her knowledge a statistical sense), but could be explained ies), where the profiles tend to be “Gauss- and skills of optimizing products and through models of the unified scheme for ian-like” but with definite indications of quality control to use for the benefit AGN. Future work will involve a more rotation in the form of small horns or of the Department of Space and Atmo- complete collection of infrared data for flat tops. Additionally, there are several spheric Sciences (SAS) at the Observa- all galaxies with HI data available, to “lopsided Gaussian” profiles for galax- tory. Her project titled “The New and allow better statistical studies, and also to ies, where the velocity widths favor two- Improved World of SAS” encompassed examine the cross-comparison between horned profiles. A plausible interpretation several smaller projects, most of which different classes of galaxies. is an imbalance of gas in the galaxy. were done under the guidance of Sixto Samantha will present her results at González. Among her main contributions Further work will involve calculation the winter AAS meeting in Seattle. to the group are creation of a World Days of distances and HI masses of the galax- Worksheet to replace the conventional ies and study of the Tully-Fisher relation. observing log books. Ingrid undertook Rebecca presented her results in a poster the rather tedious task of converting the Computer Department paper at winter AAS meeting. information from several log books into Arun Venkataraman these work sheets, and in the process Supported by Other Funds: searched for and filled in some impor- tant information that was lacking in the Storage and networking enhance- Julia Deneva (Vassar College) worked log books. ments with Paulo Freire on developing a lthough 100 GB+ disks hardly make method for the determination of the She also worked on a compilation of the news any more, they are proving orbital parameters of binary pulsars. The all the atmospheric science experiments A essential for data storage at the Obser- conventional method involved fitting a done at Arecibo from 1994 through June vatory. The Wideband Arecibo Pulsar Keplerian model to a series of period 2002, and she updated the web-based Processors (WAPPs—there are 4) is a measurements, where the accuracy is publication lists of both the SAS group particularly hungry customer, delivering limited by the number of measurements and visiting scientists. Ingrid also took and initial guess values. A recent method up to 300 GBytes a day in some current

June 2003, Number 36 24 NAIC/AO Newsletter June 2003, Number 36 25 NAIC/AO Newsletter pulsar observing programs. The Fast the several thousand hours of the survey, Ethernet (100 Mbps) interfaces on the Workshops held at the Arecibo the storage of this is likely to cost hun- machines are being upgraded to gigabit Observatory dreds of thousands of dollars. Processing speed, and local disk storage buffers to these amounts of data will also be very 1.5 TBytes each, using 6×250 GB SCSI- ALFA Pulsar Consortium Workshop challenging. The participants and their IDE RAID units. A Quantum SDLT tape institutions have, or are in the process Paulo Freire drive (160 GB native cartridge capacity of acquiring, large Beowulf clusters that at 15 MBytes/s) will soon become avail- he First ALFA Pulsar Consortium will be capable of processing these giant able for backups. TWorkshop was held on 1–2 Novem- data sets. ber 2002 at the Learning Center of the The meeting report can be dowloaded Arecibo Observatory. This meeting, the ASP cluster arrives from the pulsar consortium’s website first of a series of similar Consortium (http://alfa.naic.edu/alfa_pulsar.html). The Berkeley/Princeton/UBC-developed meetings aimed at several different areas Jim Cordes has been elected as Con- computing cluster, christened the ASP of radio astronomy, was aimed at forming sortium Chair and Paulo Freire as the (Arecibo Signal Processor) is here! The a world-wide consortium of researchers Consortium’s point of contact at NAIC. machine consists of nineteen dual-Xeon- with an interest and capacity to imple- The consortium has also created five CPU chasses, with an integrated gigabit ment large-scale pulsar surveys. ethernet switch. Initial interfacing to the different subcommittees charged with ABPP (Arecibo-Berkeley Pulsar Proces- The participants were particularly survey optimization (head: Jim Cordes) sor) has just been completed as of this excited by the prospect of a large-scale data archiving (head: Vicky Kaspi), data writing. The group’s first priority is to survey of the galactic plane visible from acquisition (head: Ingrid Stairs), software use the machine for high-precision pulsar the Arecibo telescope made with the new (provisional head: Vicky Kaspi) and timing with realtime coherent dedisper- ALFA beam array, at frequencies of 1400 follow-up observations (head: Bryan sion over a 128 MHz bandwidth per- MHz. This has the potential to find some- Gaensler). These have been maintaining formed by the cluster nodes. thing like 1000 new pulsars, a number of e-mail contact and have recently begun the same order of magnitude, but larger, a pilot survey to test some of the aspects than that of the Parkes Multibeam survey related to the data management, RFI exci- CIMA observing interface (PMB). sion and data processing, i.e., the whole Jeff Hagen’s re-engineered telescope user data pipeline. The Consortium has recommended interface, CIMA (http://www.naic.edu/ that a back-end be built that can use the ~jeffh/cima.html) has been in use for full 300 MHz bandwidth of each of the SKA International Meetings several months and will replace the seven ALFA receivers, for maximum sen- old “aocontrol” GUI. Jeff had earlier Yervant Terzian sitivity to weak pulsars. The consortium employed a “multicast” technique to has also agreed that, in order to increase uring January 16 to 19, 2003 the make instantaneous telescope status the sensitivity to millisecond pulsars International Square Kilometer information accessible to any point on D compared to previous surveys (in this Array Steering Committee (ISSC) met the Observatory network. These tools case, increasing the detection volume for at the Arecibo Observatory to consider should facilitate integration of visitor- this kind of object by a factor of about the proposed SKA designs and to discuss provided instruments. one hundred compared to the PMB), the SKA related policy issues. More than 20 ALFA pulsar survey should be conducted members and guests participated includ- ing leading radio astronomers from Data archive search tools with a faster sampling rate (64 µs) and, more importantly, with a spectral resolu- Europe, Australia, South Africa, Japan, Phil Perillat has developed search tools Canada and the U.S. Many attendees for the Observatory spectral-line data tion of 1024 channels over the 300 MHz of the ALFA band. This represents a were visiting the observatory for the first archive using the IDL platform (http: time. The SKA timetable calls for a selec- //www.naic.edu/~phil/talks/ausac03/ ten-fold increase in spectral resolution compared to the PMB, which enables tion of the construction site by the end of talk.pag1). Together with Phil’s IDL 2005, and a final design selection by the package for the 50 MHz correlator, the detection of millisecond pulsars at ten times larger DMs, as the dispersive end of 2007. Construction of the project users can perform a wide variety of data may begin by the end of the decade. The reduction and “mining” operations over smearing across each channel is ten times smaller. stipulated SKA frequency range is from the entire set of data taken over several 150 MHz to 22 GHz. It is not likely that years. A Web interface for position- This increased sensitivity to mil- a single design can accommodate this keyed searches, based on the IDL tools, lisecond pulsars comes at an enormous entire band, and hybrid models are being is under development by Gomathi Thai. cost: the ALFA pulsar survey is likely investigated. The next International SKA to produce near 1 Petabyte of data over Workshop and ISSC meetings will take

June 2003, Number 36 26 NAIC/AO Newsletter June 2003, Number 36 27 NAIC/AO Newsletter and Puerto Rico. The attendance of five graduate and one undergraduate student were fully supported by the conference organizing committee—several senior scientists were similarly supported. The workshop was made possible thanks to the support of the National Science Foun- dation (NSF), the Air Force Research Laboratory (AFRL), and the Arecibo Observatory. The Scientific Organizing Committee included Dr. Edmond Murad (AFRL), Prof. Iwan Williams (Univer- sity of London), Prof. John D. Mathews (Penn State University) and Dr. Diego Janches (AO). Topics concerning the aeronomical and astronomical issues related to detec- tion and study of the micrometeor influx in the upper atmosphere were treated in detail. Issues addressed included the micrometeor velocity distributions and Participants in the SKA International Meetings. the presence of hyperbolic , place in Geraldton, Western Australia at on February 5 – 8, 2002. The meeting, mass fluxes and their relation the end of July 2003. held at the Ángel Ramos Foundation to upper atmosphere metallic layers, Learning Center, provided an opportunity and radio science issues surrounding Arecibo was the perfect meeting to discuss astronomy outreach initiatives radar study of meteors. The latter topic place to contemplate the largest radio that are being developed by the NASA concerned the differences and similari- telescope of the future. Many thanks Goddard Space Flight Center (GSFC), ties between radar meteor observations to the Observatory and its staff for their the Arecibo Observatory and the Univer- using traditional trail-echo radars and gracious hospitality. sity of Puerto Rico. Twenty-one scien- high power, large aperture systems, in tists, engineers, and educators from these particular the presence and/or absence NASA Education and Outreach Work- institutions shared different examples of of observational biases in each tech- shop for Scientists and Engineers education and outreach activities that are nique. A complete list of speakers as being implemented. Participants had the well as the workshop photo gallery is José L. Alonso opportunity to tour the Observatory and available online at (http://www.naic.edu/ he Arecibo Observatory hosted the meet our staff. ~djanches/radarWorkshop). As a result TNASA Education and Outreach of the conference, a special issue in Workshop for Scientists and Engineers Atmospheric Chemistry and Physics is Synopsis of the 10-12 in preparation. Deadline for manuscript March 2003 Arecibo submission is October 1, 2003. Radar Meteor Workshop Diego Janches 1st Workshop of the Extragalactic n March 10-12, 2003 ALFA Consortium the Radar Meteor O Karen O’Neil Workshop was held at the Ángel Ramos Foundation hirty members of the Extragalac- Visitor Center at the Are- Ttic ALFA (E-ALFA) consortium, cibo Observatory (AO). representing 9 different countries and Over 50 participants from 22 institutions, met in Arecibo during 10 different countries 14–17 March, 2003 for the first E-ALFA attended, including USA, consortium meeting. The first half of the Israel, Czech Republic, workshop was devoted to organized talks Russia, Australia, Sweden, and discussions, while the second part Participants in the NASA Education and Outreach Workshop. England, Japan, Canada was spent in discussion.

June 2003, Number 36 26 NAIC/AO Newsletter June 2003, Number 36 27 NAIC/AO Newsletter 2003. Another meeting of the consor- tium is planned for Fall, 2003. Summaries from the meeting, a list of participants, a description of the white paper, etc. are available on-line at (http://alfa.naic.edu/extragal/meeting1/ results.htm).

Galactic-ALFA (GALFA): The First Consortium Workshop Chris Salter he Galactic-ALFA (GALFA) Con- Tsortium is an organization that aims at coordinating Galactic HI, Continuum, and Recombination Lines studies to be made with the Arecibo L-band Feed Array (ALFA). Twenty-five members of the GALFA

Participants in the Radar Meteor Workshop. Consortium, representing 16 institutions from 5 different countries, met in Are- The talks began with the staff of Are- • Very Deep, which will look at only cibo between 21 and 23 March, 2003 cibo Observatory providing a great over- ~0.4 sq. degrees of the sky, but will to formally constitute the Consortium. view of both the Arecibo telescope and be designed to detect galaxies with An organizational structure was agreed 9.5 the ALFA system. We also heard talks MHI = 10 M8 out to z = 0.015. upon, with Paul Goldsmith (Cornell) as by members of the Pulsar and Galactic A “white paper,” discussing the basics the elected Chair of the GALFA consor- Consortia describing observing projects of the surveys, consortium organization tium. in which their groups are interested, and guidelines, etc. is being drafted by as well as a number of talks from the The three sub-consortia for Galactic the workshop participants and should be E-ALFA consortium members on their HI, recombination-line and continuum available to the community by 1 July, experience with large scale surveys (both studies will be led by Snezana Sta- in the radio and optical) and on potential ideas for E-ALFA surveys. During the meeting discussions we identified five distinct surveys of inter- est: • Fast all (Arecibo) sky • Galaxies and Environment, to exam- ine properties of galaxies in a wide variety of environments, including the Virgo Cluster, Canes Venatici, around large, local galaxies, and around dwarf galaxy groups • ZOA, to look at the large, local struc- ture in the ZOA • Deep Strip, a 1×300 degree survey designed to trace the HIMF to at least 1 magnitude fainter than previ- ous surveys and across a variety of environments Participants in the Extragalactic ALFA Consortium Workshop.

June 2003, Number 36 28 NAIC/AO Newsletter June 2003, Number 36 29 NAIC/AO Newsletter March 2003 meeting, include the fol- lowing: § Galactic HI: 1. HI Low Latitude Study of the Galac- tic Plane, Study of Line Wings, Self- Absorption 2. High Latitude Clouds, Turbulence 3. Magellanic Stream, Halo clouds 4. HI disk-halo interaction 5. HI in and around molecular clouds 6. HI in multiwavelength studies of the ISM (aka HI & FUV) 7. HI in cold clouds 8. Mapping Galactic Magnetic Struc- ture. § Recombination-line Studies. Participants in the Galactic-ALFA Consortium Workshop. § Continuum Survey: Total Intensity and nimirovic (Berkeley), Yervant Terzian During the first Consortium meeting, Linear Polarization. (Cornell) and Russ Taylor (Calgary) other points that were addressed included respectively. More details on the orga- determining local Arecibo “Points of The Second GALFA meeting will nization, meeting proceedings, etc. are Contact” for GALFA Consortium activi- take place at Boston University on the to be found via: (http://alfa.naic.edu/ ties. The individuals are: 18th of June, immediately following the alfa_galactic.html). Membership of the Boston University conference on “Milky > Murray Lewis ([email protected] GALFA consortium is still open (see Way Surveys: The Structure and Evolu- — Galactic HI) http://alfa.naic.edu/consort/join.html), tion of Our Galaxy” (June 15-17, 2003). and we encourage interested scientists > Tapasi Ghosh ([email protected] For details, see (http://alfa.naic.edu/ to join as soon as possible. There is a — Continuum) galactic/meeting2/). We expect to have lot of interesting work to be done in terms ongoing discussions about spectrometer of defining requirements (especially in > Mayra Lebrón ([email protected] requirements, software, and to continue terms of spectrometer capability), — Recombination lines). to refine the scientific case for observa- observing techniques, data reduction, Proposed Scientific directions within tions associated with the above areas of and data archiving, and we are eager the areas of interest of the different sub- interest. to get additional committed individuals consortia, which were discussed at the involved.

John Harmon ends a decade of scheduling; Héctor Hernández assumes responsibility Daniel R. Altschuler fter more than ten years scheduling the Arecibo telescope, John Harmon has Astepped down from this demanding and never-ending task. We salute the dedicated effort that John has sustained over these years. After careful consideration of our options, we have assigned this difficult task to Héctor Hernández, who has been supporting our operations with service observing activities. Héctor is in charge of placing projects on the schedule following the recom- mendations of the Arecibo Scheduling Advisory Committee (ASAC), and in coor- dination with users. The Head of Radio Astronomy, the Observatory Assistant Director, the Associate Director for SAS, and the Observatory Director will support the scheduling process, resolving all matters of prioritization, conflict, and use. Héctor Hernández

June 2003, Number 36 28 NAIC/AO Newsletter June 2003, Number 36 29 NAIC/AO Newsletter The NAIC Policy on Press Releases ne of NAIC’s missions is to keep the general public informed about the exciting research work that is being done at the OArecibo Observatory in the fields of radio and radar astronomy and atmospheric sciences. Consequently, all of our users who have research projects or results that are of potential interest to the general public are encouraged to consider publicizing them via a press release. NAIC can provide assistance with the preparation and distribution of news releases both directly and via the very experienced staff at the Cornell University News Service. If a release related to work at the Arecibo Observatory is being issued by your own or another institution then it must be coordinated with NAIC and, through NAIC, with the National Science Foundation. In this case NAIC/Cornell may also wish to issue a joint release. Information about, and assistance with, press releases can be obtained through the NAIC Director’s office ([email protected]).

led by Gordon that spent three years in Puerto Rico in Comings and Goings the early 1960s building the Arecibo Observatory, which Bienvenido a Calixto Rodríguez received its first radio signals Eddie Castro in 1963. Ewen made the first detection of atomic hydro- gen in interstellar space with the collaboration of the late Harvard physicist Edward Purcell, who was to share the 1952 Nobel Prize in physics Harold Ewen presenting the inaugural Gordon Lecture. (Photo by Tony Acevedo) for development of nuclear magnetic resonance in mea- suring magnetic fields in the Calixto Rodríguez (photo by Tony Acevedo) Inaugural William and Elva Gordon nuclei of atoms. Purcell obtained a grant Lecture held at Arecibo Observatory of $500 from the American Academy of alixto joined the Electronics Depart- Daniel R. Altschuler Arts and Sciences to build the horn Cment in March, 2003 as a Receiv- antenna. Ewen then designed the antenna er / Electronics Engineer. He graduated n November 12 of 2002 we inaugu- and the mixer and receiver, which used a from the University of Puerto Rico, rated the annual lecture series named I frequency-switching technique to cancel Mayagüez, where he obtained a BSEE for William E. Gordon and his wife Elva. out systematic effects, a novel technique degree (Telecommunications Engineer- Gordon was a professor of Electrical for astronomy at the time. ing) and with an MBA degree (Opera- Engineering at Cornell University, Ithaca, tions Management – Statistical Process N.Y., when he conceived of an instrument After completing his doctorate, Ewen Control) from the Río Piedras Campus. to study the properties of the ionosphere, joined the Harvard faculty and was co- He is a CIAPR (Colegio de Ingenieros y the Earth’s upper atmosphere. director of the Harvard Radio Astronomy Agrimensores de PR) licensed Engineer Project from 1952 to 1958. He left Har- Harold Ewen, a retired engineer who (PE). During his 14 years of professional vard in 1982 to devote himself to his was a doctoral candidate at Harvard career, he had the opportunity to work in two companies, Ewen Knight Corp. and University in 1951 when he designed the Telecom Industry (PR & USA) where Ewen Dae Corp., which provided radio and built a horn antenna that made the he developed an expertise in fiber optics equipment for major academic, govern- first detection of hydrogen radio emis- and telecom networks (including C-band ment and industrial research laboratories. sion from interstellar space, gave the satellite earth stations). He also worked Since 2001 he has been a research profes- inaugural lecture. The lecture was held for the Department of Commerce (US sor at the University of Massachusetts. in the Ángel Ramos Foundation Visitor Patent & Trademark office) as a Patent His famous horn antenna is now at the Center at the Observatory to an audience Examiner in Washington, DC. Calixto National Radio Astronomy Observatory, of about one hundred visitors. will be working in several areas at the Green Bank, W.Va. Arecibo Observatory including radio The lecture series is endowed by astronomy receivers, cryogenics, RFI another Arecibo pioneer, engineer Tom mitigation and timing–synchronization Talpey, and his wife, Elizabeth. Talpey systems. was a member of the engineering team

June 2003, Number 36 30 NAIC/AO Newsletter June 2003, Number 36 31 NAIC/AO Newsletter In October 2002 he married Mayra Lebrón (see below) and two months later they moved to Puerto Rico to start a new experience. We want to wish them a happy and long stay in Arecibo.

Adios a Rob Wilson Sixto González Mayra Lebrón (photo by Tony Acevedo) Rob Wilson left in May after Award for Hijos de las Estrellas spending 9 months at Are- Astronomía de la Universidad Nacional cibo. Rob was a recipient of Autónoma de México (UNAM). Her “Hijos de las Estrellas”, the book written by the CEDAR post doc award thesis advisors for her doctorate were Daniel Altschuler (also as Children of the Stars) and spent the first year at Drs. Luis Rodríguez and Susana Lizano, and published by Cambridge University Press, Penn State University and the thesis being entitled “A Study of the was awarded the second prize for the best book finished his term here. While Gas around High-Mass Young Stars”. of the year 2001 by the Institute of Puerto Rican at Arecibo he primarily studied Between 2000 and joining NAIC, Mayra Literature. According to Eduardo Morales Coll, E-region phenomena in partic- was a Postdoctoral Research Fellow at president of the Institute, it is the first time in the ular the relationship between the MPIfR, Bonn, working within their history of these awards, started in 1938, that a book sporadic-E, sudden atom layer Millimeter Astronomy Group. While in of this genre is recognized. enhancements, and turbulence Bonn, she worked on photodissociation In the photo, Eduardo Morales Coll, President as exhibited in quasi-periodic regions and regions of high-mass star of the Institute of Puerto Rican Literature hands coherent echoes observed by formation using carbon recombination award to Daniel. (photo courtesy of the the Institute VHF radars. line and molecular line observations. for Puerto Rican Literature) Bienvenida a Mayra Lebrón Since joining us in Arecibo, Mayra Bienvenido a Giacomo Comes Chris Salter has been very active in helping with the initial organization of the Galactic ALFA Eddie Castro Mayra Lebrón joined the staff of the Radio Astronomy Department as a (GALFA) Consortium, taking a leading Giacomo Comes joined the Electronics role with Yervant Terzian in the setting Department as an engineer April 16. He Research Associate in December 2002. She is a native of Puerto Rico, hailing up of the GALFA recombination-line studied in Italy in the Polytechnic of Bari, subconsortium. Mayra has also taken where he obtained a degree in Electronic from the town of Maunabo on the east- ern coast of the island. She obtained her over as Friend of our X-Band receiver. Engineering in 1992 with full marks. After only six months here, it is already He has worked in Bari (Italy), Stras- bachelor’s degree in Applied Physics from the University of Puerto Rico at hard to imagine the Observatory without bourg (France), and Bonn (Germany). Mayra’s energetic presence. At the Physikalisches Institut at Bonn Humacao, and also spent 10 weeks at University he was system administrator the Arecibo Observatory as one of our In welcoming (or should I say “wel- of a chip-design UNIX cluster as well summer students. coming back”?) Mayra to our ranks, we as a chip-design engineer for more than Mayra got both her Master’s also extend our greetings to her hus- seven years. degree and Ph.D. from the Instituto de band, Giacomo Comes, who has joined our Electronics Department. Also to be mentioned are their “instantly acquired” family of Lady and Rex, the dogs, and Charcoal, the kitten.

Felicidades en su retiro a Antonio Crespo Don Campbell It is always hard to farewell someone who for many years has been both a valued colleague and a major contribu- tor to the Observatory’s success. This Giacomo Comes (photo by Tony Acevedo) Rob Wilson (photo by Tony Acevedo) is certainly true for Tony Crespo. Tony

June 2003, Number 36 30 NAIC/AO Newsletter June 2003, Number 36 31 NAIC/AO Newsletter have been obtained. Everyone involved about everything else really! Many of in planetary radar studies with Arecibo is our readers will have benefited during indebted to Tony for his dedication to the their Arecibo stays by having had Karen success of the program and we all wish as their “Friend of the Telescope”. She him well for the future. was also a major player in many local organizing committees for conferences Buena suerte a Karen O’Neil and workshops at the Observatory, and Chris Salter took a major part in the establishment of the Extragalactic ALFA (E-ALFA) Con- sortium. In this latter respect, we should not forget that it was Karen who coined Antonio Crespo (photo by Tony Acevedo) the acronym, ALFA. started working at the Observatory in Now, this West Virginian girl returns 1973 as a telescope operator. How- to her home state, taking up a position ever, his strong interest in electronics on the scientific staff at Green Bank. led to his being transferred in 1975 to Happily, her husband, Paul, a lecturer the maintenance department to work in Physics at the University of Puerto with Tom Dickinson as an electronics Rico, Arecibo, in recent years, has also technician helping to maintain the then joined the Green Bank staff in their Soft- new 420 kW S-band transmitter and low Karen O’Neil (photo by Tony Acevedo) ware Development Division. Karen and noise maser amplifiers used for planetary Paul, we miss you both badly, not only studies. Talent and enthusiasm brought Sadly for NAIC, Karen O’Neil left us workwise but socially too. Come back rapid promotion first to manager of the in January 2003 after over four years soon — we are only a short “hop” away Higuillales interferometer antenna site in with the Radio Astronomy Department — and don’t forget that “El Perro Tuna” 1977 and then, in 1981, to engineer with at Arecibo. Her arrival in October 1998 needs to keep up his Spanish from time responsibility for the S-band transmit- was heralded shortly before by Hurricane to time! ter and maser system. This was Tony’s Georges which made Arecibo (and the title until he retired in early May but it whole of Puerto Rico) sit up and take Muchas gracias a Slava Slysh does not describe the full range of his notice. Karen certainly lived up to this Chris Salter contributions. In addition to looking “whirlwind introduction” with her At the turn of this year, Professor Slava after the transmitter, he was involved remarkable level of energy and proac- Slysh departed the shores of Puerto Rico in many other activities of importance tive approach to all situations. Coupling to return to the Astro Space Center of the to the Observatory, such as supervising these aspects with her deep astronomical Lebedev Physical Institute in Moscow. the upgrading and maintenance of the insight and extensive technical abilities, Slava spent 15 months with us at Arecibo, antennas and transmission lines of the she has been a unique asset to the Obser- and in contributing his remarkable depth Islote High Frequency (HF) transmitting vatory. of experience and astronomical insight to facility and designing and supervising the Karen is an expert in the study of our operations did much towards raising installation of the Observatory’s security Low Surface Brightness galaxies, her the scientific and technical temper of the camera system. Tony was, of course, also contributions to the topic having fea- Observatory. While with us he pursued heavily involved with the design, pro- tured in many of the “Astronomical polarization observations of Galactic curement and installation of the new 1.0 Highlights” sections in this Newsletter OH masers (see Newsletter No. 34), and MW S-band transmitter as part of the over recent years. However, it is hard to recent upgrading of the Arecibo telescope remember that she joined us with a track and has been responsible for its operation record mainly as an optical astronomer. and maintenance ever since. It speaks volumes that on arrival in Are- Without Tony Crespo’s willingness cibo, she immediately began contributing to devote whatever time it took, day, in a major way to our operations at this night or weekend, to keep the S-band “very radio astronomical” observatory. transmitter operational, the tremendous Apart from her astronomy, Karen was the success rate of the Observatory’s plan- newsletter co-editor for 1 1/2 years; she etary radar observations could not have contributed immensely towards our web been achieved, and many important con- pages, system documentation, receiver tributions to planetary science would not calibration, data reduction approaches, control system interfaces, as well as just Slava Slysh (photo by Tony Acevedo)

June 2003, Number 36 32 NAIC/AO Newsletter June 2003, Number 36 33 NAIC/AO Newsletter line searches and other molecular-line herent scatter radar and passive optical tists, postdoctoral fellows and graduate studies between λ3 and 7.5 cm (e.g. see sensors; resonance LIDAR probing students, as well as over 200 visiting the Astronomy Highlights in this issue). of the mesosphere; and high altitude scientists per year. In addition, physics He also made significant contributions protonospheric investigations using and engineering faculty and students towards understanding the optics of the UHF and VHF radars. An experimental of the University of Puerto Rico have upgraded telescope, and contributed background in multiple remote sensing a cooperative research and educational meaningfully to discussions on the future techniques, such as radar and optics, association with the Observatory. NAIC of NAIC. would be advantageous. and the Arecibo Observatory are operated by Cornell University under a coopera- Applicants should send a resume Slava’s keen sense of humor and great tive agreement with the National Science including a list of publications, the friendliness will be much missed at the Foundation. Observatory. He and his wife, Elvira, names of three references, and a plan for lived in the small settlement of Juego research activity that would be conducted The Head of Radio Astronomy is de Bola while they were with us, where at Arecibo. These materials should be responsible for promoting observing Elvira painted some enchanting canvases forwarded to the Office of the Direc- capabilities, supervising the Arecibo of the village. Slava and Elvira, we would tor, NAIC, Cornell University, Space staff radio astronomers, supporting and like to wish you all the very best back Sciences Building, Ithaca, NY 14853- encouraging the scientific staff in their in Moscow from all of us here. We only 6801. For more information please con- personal research, monitoring the perfor- hope that you were able to “import” a tact Sixto González ([email protected]). mance of the telescope and its instrumen- little of the Caribbean sunshine with you NAIC is operated by Cornell University tation to maintain data reliability (e.g. on your return home to brighten those under a cooperative agreement with the telescope pointing and calibration), and dark winters? National Science Foundation. EOE/ arranging for the provision of assistance AAE. For further information about to visiting astronomers, as needed, to NAIC and the Arecibo Observatory see help them realize their research goals. In (http://www.naic.edu). consultation with the NAIC staff astron- Job Openings omers and the community of users, the Head of Radio Astronomy will develop Head of Radio Astronomy — Senior programs for instrument development, Postdoctoral Research Associate in Research Associate software, and user services. Space and Atmospheric Sciences he National Astronomy and Iono- ne postdoctoral position in the Tsphere Center (NAIC) has an open- Importantly, the Head of Radio Oarea of atmospheric science, with ing for the Head of the Radio Astronomy Astronomy is expected to use the Are- two-year tenure, is currently open at the research program at the Arecibo Observa- cibo research facilities in his or her own Arecibo Observatory in Puerto Rico. tory in Puerto Rico; the appointment will research endeavors and, for that reason, The starting date is flexible and review be made at the level of Senior Research we particularly encourage applications of applications will begin immediately. Associate for a period of 5 years, with from individuals with observational This position will remain open until renewal based on appropriate review. interests in such areas as pulsars, HI and filled. Applicants should have a doctoral NAIC is an NSF-funded National Center OH in our galaxy and external galax- degree in atmospheric or physical science for research in radio and radar astronomy, ies, molecular probes of star formation, or in a related engineering field, obtained and in atmospheric science, accepting and high sensitivity VLBI. A 7-element within the last few years, and have abil- observing proposals from scientists multibeam system at 21 cm is scheduled ity and interest in pursuing independent worldwide. The Arecibo 305-m tele- for initial observations in late 2004 that research. As a staff member at Arecibo, scope has recently been upgraded with will provide additional research oppor- the successful candidate will also be a Gregorian reflector system and new tunities. expected to assist visiting observers in instrumentation that permits observa- A Ph.D. in astronomy or a related field his or her area of specialty, and to help tions within a frequency range spanning is required. The successful candidate will define and implement improvements in 300 MHz to 10 GHz. This upgrade has be an employee of Cornell University, instrumentation and procedures. resulted in significant improvements in and hence eligible for all applicable available bandwidths, system noise and We will consider applications in University/Observatory benefits. Salary gain. all specialized areas of atmospheric and benefits are attractive and include a research. However, specific areas that The Arecibo Observatory is located relocation allowance. Details will depend we are most interested in reinforcing our in the karst hills of the beautiful Carib- upon the candidate’s qualifications and capabilities at Arecibo include: studies bean island of Puerto Rico. A stimulat- experience. Application evaluations of the F- and E-region ionosphere and ing research environment is provided by are currently in progress. Please send thermosphere utilizing combined inco- approximately 20 resident staff scien- a complete resume of academic, profes-

June 2003, Number 36 32 NAIC/AO Newsletter June 2003, Number 36 33 NAIC/AO Newsletter January 14, 2003, A. R. Taylor, Uni- October 17, 2002, Paulo Freire, sional and personal data, a research plan, versity of Calgary, “The International “Recent results on pulsars presented in and names and contact information of at Galactic Plane Survey” Crete” least three references, to: The Director, December 02, 2002, Paul Jones, National Astronomy and Ionosphere ATNF, Australia, “The search for bio- Center, Cornell University, Space Sci- molecules in Sagittarius B2 with the ences Building, Ithaca, NY 14853-6801. Australia Telescope” EOE/AAE. For further information about NAIC/Arecibo Observatory, see (http:// December 03, 2002, Maria Hunt, www.naic.edu). Univ. of New South Wales, “Massive Star Formation from Colliding Molecu- lar Clouds: The case for RCW 36 and RCW 57” Recent Colloquia November 19, 2002, Geoff Wright, May 14, 2003, Steve Torchinsky, Univ. of Sussex, UK, “Feedback Model Canadian Space Agency, “The Odin for Radio Pulsars” satellite: design, integration, test, and some results” November 18, 2002, Joanna Rankin, Univ. of Vermont, “Subbeam Circulation May 13, 2003, R. Ramachandran, and the Physics of Pulsar Emission” Berkeley University, “Dynamical Proper- ties of Polarization in Pulsar Radiation” November 14, 2002, Marshall Cohen, Caltech, “101 Superluminal Sources” May 8, 2003, Leslie Sage, University of Maryland, “How to publish a paper November 13, 2002, Harold Ewen, in Nature” UMass Amherst, “Radio Telescopes I’ve Known” April 3, 2003, Avinash Deshpande, Arecibo Observatory, “Vela, its X-ray November 7, 2002, Carl Heiles, UC nebula and the polarization of the pulsar Berkeley, “The Warm and Cold Neutral radiation” Media of the Galaxy” March 18, 2003, Ed Salpeter, Cor- November 4, 2002, Dan Wert- nell University, “Heavy Elements in the heimer, UC Berkeley, “Searching For Galaxy and Tuberculosis in the USA” ET With Four Million Collaborators: SETI@home, SERENDIP, SEVENDIP, February 21, 2003, Rob Wilson, SPOCK and Astropulse” AO-NAIC & Penn State Univ., “Recent Observations of Atomic Layer Enhance- October 29, 2002, Diego Janches, ments and Temperatures with the Arecibo Penn State/AO, “Diego’s Turn (on-going Potassium Lidar” debate on meteors)” February 20, 2003, Josef Höffner, October 25, 2002, John Mathews Leibniz Institute for Atmospheric Phys- and Diego Janches, Penn State/AO, ics, Germany, “Observations of NLCs, “Reply” temperatures and PMSEs at Svalbard, October 24, 2002, Ulf von Zahn, 78° N” Leibniz-Institute of Atmospheric Phys- February 6, 2003, Emmanuel Mom- ics, “Remarks on the total meteoritic jian, NRAO, “Sensitive VLBI con- mass flux into the Earth’s Atmosphere” tinuum and HI absorption observations October 24, 2002, Erik Muller, ATNF, of interacting/merging galaxies” Australia, “An analysis of the HI in the Magellanic Bridge”

The NAIC/AO Newsletter is published three times a year by the NAIC. The NAIC is operated by Cornell University under a cooperative agreement with the National Science Foundation. Tapasi Ghosh and Jonathan Friedman, editors. Contact: [email protected] or [email protected]; http:www.naic.edu.

June 2003, Number 36 34 NAIC/AO Newsletter