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 article is dedicated to the latest reports of available comets for observations, current state of those comets, (PanSTARRS) C/2011 L4 future predictions, & projections for 9 October 2012 observations in comet astronomy! © Erik Bryssinck, BRIXIIS Observatory – Kruibeke, Belgium Winter Season – Jan/Feb 2013 The Professor Comet’s Report 2 The Current Status of the Predominant Comets for Jan/Feb 2013! Comets Designation Orbital Magnitude Trend Observation Constellations Visibility Period (IAU – MPC) Status Visual (Range in (Night Sky Location) (alt. ≥ 30˚) Lat.) All times CDT LEMMON C/2012 F6 C 7.3* Brightening 30˚N - 90˚S Moving S thru Centaurus until 16 Jan Visible for lower (11 Jan) Rapidly and then across Crux until 22 Jan & moves latitudes of N across Octans thru Mid February hemisphere until early Feb! PanSTARRS C/2011 L4 C 8.6* Bright and N/A Moving ESE thru Corona Australis Lost in the (13 Jan) Steady until 31 Jan & along the outer boundaries of Sagittarius & Daytime Telescopium: 31 Jan – 9 Feb Across the S frontier of Microscopium: Glare! 10 – 16 Feb Pons – Gambart 273P/2012 V4 P 8.6* Brightening 85˚N - 20˚S Moving NNW from Scutum to Serpens 15˚≥ alt. ≥ 0˚ – SWAN (C/1827 M1) (8 Dec) Gradually Cauda and the NE region of Ophiuchus (5:30 – 6:30) AM LINEAR C/2011 F1 C 9.0* Somewhat N/A Moving ESE across the S region of Lost in the (4 Nov) Bright, but Sagittarius thru Mid Feb! possibly Daytime Steady Glare! LINEAR C/2012 K5 C 9.9* Fading 70˚N - 60˚S Progressing SSW thru the W region of the alt. ≥ 30˚ (12 Jan) Rapidly ‘Winter Hexagon’ from Taurus to Orion (6:30 PM – 1:00 AM) and then well into Eridanus thru mid 30˚≥ alt. ≥ 0˚ March! (1:00 – 3:00) AM McNaught – 262P/2012 K7 C 10.8* Fading 65˚N - 60˚S Moving E thru Cetus until Early Feb alt. ≥ 30˚ Russell (3 Jan) Noticeably and then thru the N region of Eridanus (6:30 – 9:15) PM until Late March 30˚ ≥ alt. ≥ 0˚ (9:15 – 11:30) PM *Visual Magnitude determined from last known field observation report! Comets with visual magnitudes fainter than 12 , more suitable for observing in the Southern hemisphere , or the tropics are not reported on this list! Winter Season – Jan/Feb 2013 The Professor Comet’s Report 3 The Current Status of the Predominant Comets for Jan/Feb 2013! (Continued) Comets Designation Orbital Magnitude Trend Observation Constellations Visibility Period (IAU – MPC) Status Visual (Range in (Night Sky Location) (alt. ≥ 30˚) Lat.) All times CDT Schwasswann – 29P P 11.0* Very Diffuse 50˚N - 50˚S Undergoing another ‘tight retrograde’ loop 0˚≤ alt. ≤ 30˚ Wachmann 1 (8 Jan) and Fading between Spica & Hydra and lasting thru (1:45 – 4:45) AM Gradually mid September 2013! alt. ≥ 30˚ (4:45 – 6:30) AM Hergenrother 168P P 11.3* Fading and 90˚N - 25˚S Moving E thru the E region of alt. ≥ 30˚ (8 Dec) Diffusing Andromeda until Early Feb and then (6:30 – 11:20) PM Rapidly across the central region of Perseus thru 30˚≥ alt. ≥ 0˚ late March! (11:20 PM – 2:15 AM) McNaught C/2011 R1 C 11.4* Bright and 35˚N - 55˚S Undergoing a slight reversal of motion 0˚ ≤ alt. ≤ 30˚ (15 Oct) Steady from NNE to NNW moving thru the W (4:00 - 6:30) AM central region of Scorpius LINEAR C/2012 L2 C 11.8* Slight 90˚N - 15˚S Progression SE thru the central region of alt. ≥ 30˚ (3 Jan) Bright, but Cassiopeia until the end of Jan & into the E (6:30 – 11:00) PM Fading region of Andromeda 30˚≥ alt. ≥ 0˚ (11:00 PM – 6:30 AM) Bressi C/2012 T5 C 11.9* Still Visible, 40˚N - 60˚S Progressing SW from Cetus until Mid 30˚ ≥ alt. ≥ 0˚ (11 Jan) but Jan and across the N & W regions of (6:30 – 10:00) PM Diffusing Sculptor until Mid Feb Slowly *Visual Magnitude determined from last known field observation report! Note: Range of Latitudes for availability for visible & photographic observations depend solely on available times during astronomical twilight beginning and end! Comets with visual magnitudes fainter than 12 , more suitable for observing in the Southern hemisphere , or the tropics are not reported on this list! Winter Season – Jan/Feb 2013 The Professor Comet’s Report 4 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. {El. ( ˚ )} 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. (Ph.) 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!) Winter Season – Jan/Feb 2013 The Professor Comet’s Report 5 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 Winter Season – Jan/Feb 2013 The Professor Comet’s Report 6 A Synopsis of the Predominant Comets for Winter 2013! This winter season there a variety of comets to observe in the skies for the new year with about eleven such comets ranging in recorded apparent magnitudes from 7 – 12! Two of these comets C/2011 L4 (PanSTARRS) and 273P/Pons – Gambart are lost in the daytime glare of the Sun for the next couple of months and one C/2012 F6 (LEMMON) is only visible to observers in the Northern hemisphere at latitudes below 30˚ N only until early Feb and will not reappear until it is in the constellations of the Autumnal sky around May. Among these comets the only one of valuable observations thru the end of February is C/2012 K5 (LINEAR) which is rapidly receding away from both the Sun and inner solar system. C/2012 K5 is currently in a SSW track thru the constellations between Orion and Taurus, but will soon slow down significantly as it moves into the northern region of Eridanus and undergoes a partial retrograde effect which will have it turn SE by the beginning of late February and then move towards the rabbit (Lepus) around the evening of 16/17 April 2012. The comet is already close to 10th magnitude, so it will become even more challenging to observe the constellations set even earlier in the western skies upon the ever approaching glow of the Spring evenings as daylight hours will only increase with the passing of the Winter Solstice.