HUBBLE HISTORY

would use up precious HST annotate each data tape (including measure positions and magnitudes of The Birth of resources, which were in critically object description, image quality, and all objects, develop the required the Snapshot short supply before launch. The other science), and that we would deliver software, measure and report members of the working group felt the annotated tapes for public regularly on the gyro performance Programs that STScI resources should be distribution every three months. and the telescope pointing focused on the high priority GTO and Rodger agreed to develop the accuracy, do the science analysis, John Bahcall, Institute for GO (general observer) programs, not capability to assign generic parallel publish our results, and deliver the Advanced Study, [email protected] on some subsidiary (albeit non- observations in the scheduling annotated tapes. proprietary) program. system. The Non-Proprietary program The situation changed drastically he Snapshot program , the first STScI was to be assigned the lowest when, after launch in April 1990, originated in a lunchtime director, saved the program from scheduling priority. spherical aberration was discovered conversation between infanticide. Calming the waters, In a January 5, 1990, meeting with in the HST images. The wide-field Rodger Doxsey and myself Riccardo persuaded everyone to Rodger, Duccio Macchetto, Larry images of galaxies no longer made in the STScI cafeteria allow him to work with me and with Petro, and Peter Stockman, we sense. But, after discussions among sometime in the spring Rodger to see if we could develop a agreed that all of the exposures the science team, we realized that of 1989. We were both late to T program in which all the work would would be made on gyro control, with we could still do a gravitational lens lunch and probably were the only be done in Princeton and no STScI no guide stars. This decision was survey of bright but distant quasars, people in the cafeteria. The principal resources would be required. motivated by our desire to have the using the sharp core of the PSF to topic of conversation was the With the enthusiastic help of least possible impact on the look for close, multiple images. expected low observing efficiency of Rodger, Jim Gunn, Opher Lahav, and overloaded STScI resources. Riccardo allowed me to revise our the HST. Rodger described the director’s discretionary time proposal extraordinary difficulty in making a and the Snapshot lensing survey schedule that would use a reasonable became one of the principal early percentage of the available time for “All hell broke loose. The instrument programs of HST. Dani Maoz was science observations. Slewing was hired as a postdoc at the Institute slow and changing instruments or PIs and other principal GTOs all argued for Advanced Study, assuming modes of observing was time responsibility for the initial technical consuming. Also, the scheduling heatedly that this project would use up and scientific analysis. software that existed in 1989 was Our survey played a minor but not very powerful. precious HST resources...” useful role in the thrilling, frustrating, I asked Rodger, without thinking and stressful early days of bringing very carefully about what I was saying, Don Schneider, I drew up a science The ‘gyro-only’ policy had a the HST observatory into routine if it would be possible for the software program (HST Program 2775, which far-reaching science implication that science observations. We obtained he was developing to insert new subsequently had many aliases we did not anticipate at the time. We frequent observations under standard objects in the holes in the schedule. I including 3034, 3092, …) which removed the star fields, since they conditions (same filters, same wondered aloud if one could improve proposed WFPC images of relatively required longer exposures. The observing time, similar objects) in the efficiency by choosing new bright quasars (463 objects), large science team decided to replace the the pre-Cycle 0 phase as part of objects, close to the directions of the angular diameter, peculiar, and star fields by exposures of bright but the Science Assessments Tests scheduled targets, from a previously interacting galaxies from the ESO and distant (Z > 1) quasars. Although program. Dani measured large tele- prepared list of interesting objects UGC catalogs (402 objects), and they were originally only a small part scope pointing errors (median error scattered over the sky. I remember selected star fields (17 areas). of the Non-Proprietary Survey, the 25 arcseconds) and large image that Rodger suddenly became very We had several meetings in the distant quasars were slated to drift rates during the exposures. quiet, thought about the question, summer and winter of 1989 to set the become our primary science program These were traced to the fact that and finally replied something like: “In ground rules for the project. Peter after the mirror problem was found. corrections for the effect of stellar principle, it is possible.” Stockman summarized the results of The Non-Proprietary Survey— aberration had not been activated these meetings in a memo dated which was dubbed the Non- in the pointing and guiding software The Snapshot program August 7, 1989. Proprietary “Snapshot Survey” by (I for the gyro-only mode. Once this was born at that lunch. The conditions for the implemen- think) Peter Stockman—was was fixed, it brought about a large The subsequent early history was tation of the program may seem approved by Riccardo for director’s reduction in failed target acquisitions stormy. I proposed the concept of a stringent by today’s operating discretionary time on a trial basis for in other HST programs. In observing “Non-Proprietary Survey” at an HST standards. We agreed that Don and I the early HST observations. Riccardo Cycles 0 and 1, we obtained science working group meeting shortly would search all fields for bright stars felt that he had fulfilled his many valuable science observations thereafter. All hell broke loose. The that might affect subsequent commitment to the HST working as the observatory performance instrument PIs and other principal observations, that we would provide group not to use significant STScI improved. Snapshot observations GTOs (guaranteed time observers; I the software and algorithms for resources for the project. We were were scheduled almost routinely. was an Observatory Scientist) all feeding the objects to the scheduling awarded a magnanimous grant of The Snapshot survey for argued heatedly that this project system, that we would process and $20,000 to prepare the target lists, gravitational lenses was initially

 22  described in Bahcall et al., ApJ, 387, first systematic measurement of the By this time, the process of finding surveys are frequently used and 56-68 (1992) and summarized, frequency of lensing among a large guide stars for targets had become contribute to HST’s effectiveness. I following a series of other papers in sample of bright quasars, especially computer intensive rather than am glad that Rodger and I were Maoz et al. ApJ, 409, pp. 28-41 in the subarcsecond image regime personnel intensive. As a result, late for lunch on that spring afternoon (1993). The survey included a total of that only HST could probe. Snapshot proposals were permitted in 1989. Ω 498 quasars (as well as star count In observing Cycle 2, STScI to make use of guide stars and could data) and provided (in addition to announced the Snapshot survey therefore cover a wider range of other significant scientific results) the mode as a standard observing option. science programs. Today, Snapshot

Hubble Spots an Icy World Far Beyond Pluto ASA’s has measured the largest object in the solar system ever seen since the discovery of Pluto 72 years ago. Approximately half the size of Pluto, the icy world is called N“Quaoar” (pronounced kwa-whar). Quaoar is about 4 billion miles away, more than a billion miles farther than Pluto. Like Pluto, Quaoar dwells in the Kuiper belt, an icy belt of comet-like bodies extending 7 billion miles beyond Neptune’s orbit. http://oposite.stsci.edu/pubinfo/pr/2002/17 Illustration Credit: NASA and G. Bacon (STScI) Science Credit: NASA and M. Brown (Caltech)

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