The Professor Comet’s Report 1 Mr. Justin J McCollum (BS, MS Physics) Lab Physics Coordinator Dept. of Physics Lamar University Welcome to the comet report which is a monthly article on the observations of comets by the amateur astronomy community and comet hunters from around the world! This C/2009 P1 Garradd with article is dedicated to the latest reports of available comets for Barred Spiral Galaxy NGC 4236 observations, current state of those comets, future 14 March 2011! predictions, & projections for observations in comet astronomy! Early Spring – April 2012 The Professor Comet’s Report 2 The Current Status of the Predominant Comets for Apr 2012! Comets Designation Orbital Magnitude Trend Observation Constellations Visibility (IAU – MPC) Status Visual (Range in (Night Sky Location) Period Lat.) Garradd 2009 P1 C 7.0* - 7.5 Fading 90°N – 30°S SW region of Ursa Major moving All Night SSW towards the SE region of Lynx. Giacobini - 21P P 9 – 10 Fading Poor N/A Zinner Elongation Lost in the daytime Glare! LINEAR 2011 F1 C 11 .7* Brightening 90°N – 20°S Undergoing retrograde motion All Night between Boötes and Draco thru the late Spring. Gehrels 2 78P P 12.2* Fading 60˚N - 20˚S Moving eastwards across Taurus Early Evening and progressing along the N edge of the Hyades Star Cluster! McNaught 2011 Q2 C 12.5 Fading 70˚N – Eqn. Currently in the S central region Early Morning of Andromeda moving NE between the boundary between Andromeda & Pisces. NEAT 246P/2010 V2 P 12.3* - 13 Possible 65˚N - 60˚S Undergoing retrograde motion All Night Steadiness in the E half of the N central region of Virgo until late June. McNaught 2009 F4 C 12.8* - 14 Steady Poor N/A Elongation Lost in the daytime Glare! *Visual Magnitude determined from last known field observation report! Comets with visually reported at visual magnitude values fainter than 13.5 are not reported on this list! Early Spring – April 2012 The Professor Comet’s Report 3 Ephemeris Data Terminology Ephemeris Term Definition (plus additional comments) Date Month and Year using the standard Gregorian calendar. TT Terrestrial Time (Day of the Month) as a substitute for the astronomical Julian date. RA (2000) Right Ascension based on the Epoch J2000 (longitudinal coordinate for the celestial sky) measured in hours, minutes, and seconds. Dec (2000) Declination based on the Epoch J2000 (latitudinal coordinate for the night sky) measured in degrees, arcminutes, and arcseconds. Delta The distance from Earth measured in AUs (1 AU = 1 Astronomical Unit = 92 955 807 mi = 149 597 871 km as the mean distance between the Earth and Sun). R The solar distance measured in AUs (the distance between the comet or comet – like body and the Sun)! Elongation Solar elongation which is the angle of separation between the observed object and the Sun as measured across the night sky as measured in degrees. Phase Phase angle between the Sun, the celestial object, and the observer on the surface of the Earth. Also known as the Sun – Object – Observer angle. M1 M1: The visual magnitude of the celestial object as observed on the surface of the Earth at sea level. (Note M1 values predicted by the Minor Planet Center can differ from actual visual reports obtain in the field!) M2 The nuclear magnitude of the Comet which is also the visual magnitude of the false nucleus. (Rarely shown on a Comet’s ephemeris data spreadsheet unless all values show a visual brightness value above 19th magnitude!) “/min The progression or motion across the sky as measured in arcseconds per minute. P.A. Position angle while undergoing motion in the celestial sky. (P.A. is the same method applied to binary stars with starts at N goes counterclockwise in an easterly direction!) Moon Phase A Numerical value for designating the phases of the Moon on a scale of (0.00 – 1.00): A New Moon = 0.00, Waxing or Waning Crescent = (0.01 - 0.49), Half Moon (1st or Last Quarter = 0.50), Waxing or Waning Gibbous = (0.50 – 0.99), & Full Moon = 1.00 Foreshortening The appearance of the comet’s tail due to the geometric orientation between the Earth and a Comet. (% Fore.) (100% means the comet’s tail is parallel with the face of the Earth where as 0% means the tail is exactly perpendicular with respect to the face of the Earth!) Early Spring – April 2012 The Professor Comet’s Report 4 All observations of comets are broken down into three factors: estimating Degree of Condensation (DC) magnitudes for light curves to predict future brightness, coma observations, and observations that concern with a comet’s tail(s). For the coma or a comet’s head there two characteristic features that are important for study: Degree of condensation (DC) and coma size measured in arcminutes. The classification system for determining the DC is based on a positive integer system from 0 to 9 as shown below. DC value Definition to numerical DC designation 0 Diffuse coma of uniform brightness 1 Diffuse coma with slight brightening towards center 2 Diffuse coma with definite brightening towards center 3 Centre of coma much brighter than edges, though still diffuse 4 Diffuse condensation at centre of coma 5 Condensation appears as a diffuse spot at centre of coma – described as moderately condensed 6 Condensation appears as a bright diffuse spot at centre of coma 7 Condensation appears like a star that cannot be focused – described as strongly condensed 8 Coma virtually invisible 9 Stellar or disk like in appearance Early Spring – April 2012 The Professor Comet’s Report 5 A Synopsis of the Predominant Comets for the New Year 2012! Comet Garradd with its progression past perihelion and perigee has now set a path to travel beyond the asteroid belt into the outer Solar system for the Spring season of 2012. The comet is now moving in a southerly direction through the western region of the constellation of Ursa Major (home to the famous ‘Big Dipper’ asterism) and expected to cross the boundary between the constellations of Ursa Major and Lynx the evening of 15 April 2012 at 23:00 CST. Prior to its crossing it will move thru the last leap of ‘the Gazelle’ (the hop of the Gazelle across Ursa Major by the pattern three pairs of stars representing the feet of Ursa Major) the Talitha stars the early morning of 14 April. Expect the comet to continue with its southerly path advancing deeper and across the eastern areas of Lynx well into mid – May. Garradd will alter course once it enters the constellation region of Cancer and head southeast, but remaining within the Crab through the early – middle of the Summer season, but confined to the NE and east – central regions of the Crab! The comet will pass closely to several stars along the SW area of Ursa Major, SE area of Lynx, and a few spiral galaxies with a visual magnitude fainter than 10.0. Look towards the spreadsheets on pages 12 & 13 for further information on the brightest stars and primary DSOs (Deep Sky Objects) that will be within the vicinity or in the same region of the sky where comet Garradd will be located for most of the Spring season! The current conditions of C/2009 P1 have it a maximum brightness of visual magnitude 7.0 last reported on March 30 with a current angular size reported between 10’ – 16’ or 10.4% - 26.6% the size of an average full Moon. The comet has a current DC value of 7 which indicates a tightly, compacted coma that allows the comet to appear to stellar – like, but lacking in the tight resolution required for it to have a well defined boundary. It is still visible in binoculars however the fan – shaped tail has been visually observed since last month. The confirmed sighting on March 28 give a field observation report with the dust tail at an angular length of 0.7˚ (42’ or ~1 1/3 full moon widths) at a PA of 40˚ orienting the tail to the NE of the coma. No visual reports have been given on the ion tail recently although the last image taken on 14 March show a 100˚ separation between the two tails. Comet Garradd’s ion tail would then be placed at a PA of 140˚; projecting SE from the coma and is faint enough to require moderate telescopes under dark sky conditions to observe it or at least the dust tail which will be a few magnitudes brighter than the ion tail. Expect Comet garradd to fade in brightness until it is about 12th magnitude around the last week of May, but position at a very low angle of altitude for northern hemisphere observers between late April thru most of June. Garradd’s solar elongation will decrease to 90˚ by 23 April and will be reduced to 60˚ by 30 May as the winter constellations start to fade into the daytime sky for the rest of Spring well into Fall Autumn! Early Spring – April 2012 The Professor Comet’s Report 6 A Synopsis of the Predominant Comets for the New Year 2012! There are no other comets that are prominent right now nor are any of the known cometary bodies currently being monitored are expected to get brighter than 8th or 8th magnitude expect comet 96P/Machholz 1 which is expected to be visible this summer during the months of July and August in the evening hours before midnight! Comet Machholz 1 is currently progressing eastward thru the northern edge of the southern constellation of Grus ‘the Crane’ and will move into the neighboring constellation of Sculptor by late April and move quickly thru the ‘Winter Hexagon’ asterisms of the winter constellations from mid – June and most of early – July lost in the daytime glare.