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 Astronomy Sketch of the Day the observations of comets by the amateur astronomy Courtesy of James & Forrest Maxwell community and comet hunters from around the world! 4 April 2012 This article is dedicated to the latest reports of available comets for observations, current state of those comets, future predictions, & projections for observations in comet astronomy! Mid Spring – May 2012 The Professor Comet’s Report 2 The Current Status of the Predominant Comets for May 2012! Comets Designation Orbital Magnitude Trend Observation Constellations Visibility (IAU – MPC) Status Visual (Range in (Night Sky Location) Period Lat.) (alt. ≥ 30˚) Garradd 2009 P1 C 8.0* Fading 90°N – 50°S S region of Lynx moving S then 8 PM – 1 AM SSE into the N region of Cancer. CDT Giacobini - 21P P 9 – 10 Fading Poor N/A Zinner Elongation Lost in the daytime Glare! LINEAR 2011 F1 C 11 .6* Brightening 90°N – 25°S Undergoing retrograde motion (1 – 5) AM CDT between Boötes and Draco thru the late Spring. LINEAR C/2011 UF305 C 11.8* Rapid 90°N – 10˚N Circumpolar comet for May (1:30 - 5:00) AM Brightening (N region of Cepheus) CDT NEAT 246P/2010 V2 P 12.3* - 13 Possible 65˚N - 60˚S Undergoing retrograde motion Sunset – 3 AM Steadiness in the N central region of Virgo CDT & S boundary of Coma Berenices until late June. McNaught 2011 Q2 C 12.5 Fading 70˚N – 25˚N Currently in the SE region of Visible at Andromeda moving ENE alt. < 30˚ (3:30 – 5:00) AM towards Perseus. CDT 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 or 13.5 are not reported on this list! Mid Spring – May 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!) Mid Spring – May 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 Mid Spring – May 2012 The Professor Comet’s Report 5 A Synopsis of the Predominant Comets for the Spring & Summer 2012! Comet Garradd is now setting in the early to mid evening in the western skies with the constellations of the winter sky as we progress thru the middle of the Spring season in the month of May! Currently the comet is continuing to fade as it moves thru the Asteroid belt on its trajectory to the outer solar system and back to its origins most likely in the Kuiper Belt. The latest field reports give Garradd a visual magnitude brightness of 8.0 as of late April. Garradd was last reported on 28 April with an angular diameter of only 5 arcminutes (~2.6% the size of an average full Moon) with a DC of 5. There are no further reports on the conditions of the fan - shaped tail given that is now much harder to see with the rapid fading of comet Garradd as the Winter constellations disappear from the night sky by the end of May. However, both Lynx and Cancer will still be visible even after sunset up until the beginning of July. Therefore, May is the month to observe at least the coma of Garradd, but the central condensate (nucleus) of the coma will end up having a stellar magnitude of 11.0 by mid June. However, some predictions place the comet’s visibility at ‘non – observable’ before the end of early June with its solar elongation decreasing from 84˚ (1 May) to 60˚ (May 30). Therefore, May is likely the last month in which to observe comet Garradd before it is lost in the daytime solar glare until it is visible again in late October, but the comet will have faded to 13th magnitude while moving south thru the constellation of Sextans! 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. However, once it is visible sometime in mid July it will be located between Lynx and Cancer low in the evening skies just after sunset with the planet Mars setting during the months of mid – Summer. As we move into the month of August the comet will have shifted its position further east towards the following in succession; Coma Berenices (25 July – 6 Aug), Virgo (6 – 7 Aug), Boötes (7 – 13 Aug), Virgo in its NE region (13 – 22 Aug), and Libra thru the end of August. Machholz 1 will reach a predicted maximum brightness of visual magnitude 7.0 by the month of July. However, the comet has a solar elongation below 60˚, so it will be difficult to see positioned at a sky altitude below 30˚ during the hours of dusk making a very difficult object to observe thru so much air and the effects of atmospheric refraction and mirage effects close to the distant horizon! Current predictions are placing this comet as a maximum brightness of visual magnitude -0.l (~6% brighter than Arcturus) and located in the constellation of Gemini the period of 1 -2 July, but with a solar elongation of 1 – 3 degrees! Mid Spring – May 2012 The Professor Comet’s Report 6 A Synopsis of the Predominant Comets for the Spring & Summer 2012! Once future prospect is in 2013 with the discovery of C/2011 L4 (PanSTARRS) discovered using 1.8m Pan – STARRS 1 RC telescope on the Hawaiian islands, USA the night of 6 June 2011 between 09:36 – 10:32 UTC or 04:36 – 05:32 AM local Hawaiian time.