the professor comet’s report 1 - north houston astronomy...

The Professor Comet’s Report

Mid Autumnal Season – Late Oct/Late Nov 2012

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,

future predictions, & projections for observations in comet astronomy!

1

Mr. Justin J McCollum (BS, MS Physics) Lab Physics Coordinator

Dept. of Physics Lamar University

168P/Hergenrother 21 October 2012

© SLOOH SPACE CAMERA, Canary Islands Observatory.


The Current Status of the Predominant Comets for Oct/Nov 2012!

Comets Designation (IAU – MPC)

Orbital Status

Magnitude Visual

Trend Observation (Range in

Lat.)

Constellations (Night Sky Location)

Visibility Period (alt. ≥ 30˚)

All times CDT

LINEAR C/2011 F1 C 9.3* (5 Oct)

Steady 40˚N - 35˚S Moving SE between the NE corner of Libra and eventually along the S edge of

the ‘Celestial Coffin’ asterism of Ophiuchus

0˚≤ alt. ≤ 15˚ (7:00 – 7:30) PM

Hergenrother 168P P 9.5* (18 Oct)

Bright & Steady

Outburst

90˚N - 40˚S

Moving NNW through the E region of the ‘Great Square’ of Pegasus for most

of October! Now moving N into the W region of

Andromeda!

alt. ≥ 30˚ (7:00 PM – 2:30 AM)

30˚≤ alt. ≤ 0˚ (2:30 – 5:00) AM

LINEAR C/2012 K5 C 11.1* (13 Oct)

Brightening N/A

Difficult to observe since the comet is so close to dusk & dawn before and after

twilight respectfully!

30˚≤ alt. ≤ 0˚ (7:00 – 8:30) PM

0˚≤ alt. ≤ 15˚ (4:30 – 5:30) PM

McNaught C/2011 R1 C 11.4* (15 Oct)

Steady, some variation

N/A

Moving NE through Lupus (the Wolf) for the rest of 2012!

Lost in the daytime glare!

N/A

LINEAR C/2011 UF305 C 11.5* (15 Sept)

Steady 90˚N - 45˚S

Progressing S through Leo Minor and turn WSE in the NW region of Leo (Mid October – Early December)

0˚≤ alt. ≤ 30˚ (12:30 – 3:15) PM

alt. ≤ 30˚ (3:15 – 5:30) AM

McNaught 260P/2012 K2 P 12.2* (9 Oct)

Steady, some variation

90˚N - 20˚S

Performing a ‘very tight’ retrograde motion in Andromeda (NE region)

(10/24 – 12/11)

alt. ≤ 30˚ (7:00 PM – 4:30 AM)

30˚≤ alt. ≤ 15˚ (4:30 – 5:30) AM

Catalina C/2012 J1 C 12.8* (5 Oct)

Faint, but steady

90˚N - 45˚S

Same region as 168P, but moving SE into the ‘Great Square’ of Pegasus!

alt. ≤ 30˚ (7:00 PM – 2:30 AM)

30˚≤ alt. ≤ 0˚ (2:30 – 5:00) AM

2

*Visual Magnitude determined from last known field observation report!

Comets with visual magnitudes fainter than 13 or those more suitable for observing in the Southern hemisphere or the tropics are not reported on this list! Mid Autumnal Season – Late Oct/Late Nov 2012

The Professor Comet’s Report 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 (% Fore.)

The appearance of the comet’s tail due to the geometric orientation between the Earth and a Comet. (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!)

3



Degree of Condensation (DC)

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

All observations of comets are broken down into three factors: estimating 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.

4



A Synopsis of the Predominant Comets for Autumn 2012! The middle of the Autumnal season for 2012 has brought astronomers and comet observers an unexpected outburst of

comet 168P/Hergenrother which acquired a peak brightness of visual magnitude 9.2 on 11 October with a maximum normalized value of 9.0 calculated for the date 2 October! The comet has moved northwestward across the eastern region of the ‘Great Square’ of Pegasus during most of the first half of October as it brightened up from 11th magnitude and has maintained magnitude range between 9.5 – 11 until mid November. Hergenrother reached a perigee of 0.423 AU (63 228 390km) during the period of (24 – 27) September and then obtained perihelion of 1.415 AU (211 508 682km) from 29 Sept – 6 October. The central nucleus is very small about 2.5 – 3 arcminutes in size (0.65% - 0.94% the size of an average full Moon) with a DC around 4 and the tail under moderately dark skies is visible as a faint, fan shaped protrusion of dust protruding about another 5 arcminutes at a P.A. of (160˚ - 170˚). This places the tail positioning to the SSE from the central nucleus which has a stellar magnitude around 8.0! The comet is now continuing on it path outwards towards the outer solar system and it moves NW into the western region of the constellation of Andromeda until the evening of November 7 and then head NE across Andromeda until early February 2013. Hergenrother will graze closely near the Andromeda galaxy (Messier 31) and the companion galaxy M 110 during the evenings of (19 – 23) December 2012. The closet approach to M 110 will be on the evening of 19 December at an angular separation ~1˚ and the same separation between 168P and M 31 on 21 December within three days of Christmas Eve! The remaining autumnal season will remain light on comets for the duration of 2012! There are other less interesting comets to observe: C/2011 UF305 LINEAR, C/2012 J1 Catalina, and 260P/McNaught all these comets are observable at visual magnitudes brighter than 13.0. For 2013 there are two possible candidates to make quite a show for comet hunters if predictions pan out for the coming new year: C/2011 L4 PanSTARRS & C/2012 S1 ISON. Right now both comets are very faint, but are destined to travel deep within the inner solar system thru 2013. C/2011 L4 PanSTARRS is the first of these two to make an appearance with a predicted magnitude of 0.5 and possible expectation of reaching a stellar magnitude brightness of -1.0 during the period of 10 – 11 March 2013! Comet PanSTARRS will progress through the skies of the late summer and early autumnal constellations through the month of March at a peak motion of 2.92˚ (~5.65 average full size Moons) per day on 6 March around the same time as PanSTARRS reaches a perigee of 1.097 AU (163 975 282 km)! Expect C/2011 L4 to stay above the 2˚/day motion from 18 February – 19 March while staying low in the southern celestial skies as observed in the northern hemisphere from Microscopium to Grus, between Piscis Austrinus and Sculptor, and finally moving NE from the W edge of Cetus into W region of Pisces! However, during its period of maximum brightness C/2011 L4 will be lost in the daytime glare as the Sun will moving across the constellations of late summer/early autumn with the comet reaching a minimum solar elongation of 15.1˚ on 11 March 2013! The best times to observe this comet while it is still bright will be after it’s perihelion passage of 0.302 AU on 10 March and when the solar elongation is greater than 45˚ from late April and into most of summer as an all night comet with a possible stellar magnitude of 0.0!

5



A Synopsis of the Predominant Comets for Autumn 2012! One remaining comet is C/2012 S1 ISON of the International Scientific Optical Network (ISON) which is located

near Kislovodsk, Russia by two scientists; Vitali Nevski (Belarus) and Artyom Novichonok (Russia) from 21 Sept 2012 at a visual magnitude of 18.8! Currently this comet is undergoing an ‘overlapping retrograde effect’ in the northern region of Gemini near the twins ‘Castor and Pullox’ from Spring 2012 thru mid Spring 2013. The last reported observation in peak brightness was 17.2 on 12 October 2012. The comet will be observable from November 2013 and thru all of January 2014 as the comet is expected to reach a perihelion of 0.051 AU (7 623 281 km) based on the IAU Minor Planet Center although some estimations place the perihelion value as small as 0.01 AU (1 494 761km or 928 246.6 mi). This means that the comet will move through the inner regions of the Sun’s corona much like that of comet C/2011 W3 Lovejoy which is spite of its designation is a long period comet and a Kreutz sungrazer who (on 16 December 2011) passed to within 140 000 km of the photosphere; a mere distance compared to the projections set for this comet of the ISON survey! C/2012 S1 will pass perihelion on 29 November 2012 while grazing very closely to Dschubba (δ Scorpii) moving eastward across the summer constellations and then head directly northward into ‘Serpens Caput’ and eventually between Hercules and Corona Borealis! The comet will reach perigee of 0.429 AU (64 125 247 km or 39 821 778 mi) on 27 December 2013 as the comet progresses into the northerly skies of the ‘circumpolar’ constellations of the northern hemisphere. It is in this period that all comet observers and astronomers of all kinds will have the possibility of observing a comet that could reach a brightness equal to that of the planet Venus between (-2 to -4.5) in visual stellar magnitude or more! Although we are still over a year away from witnessing this comet as the great event of 2013 and there are possibilities ranging from a great disappointment to greater than the highest expectations, so I advise caution at this point and there could other unexpected outbursts or surprise discoveries that could eclipse C/2012 S1 at this time! Stay tuned for future details as we all move through the remains of 2012 and into 2013!

5



Figure 1: Hergenrother’s projected path between Pegasus & Andromeda: (15 Oct 2012 – 4 Jan 2013)!

Courtesy of SkyTools 3 Profession Ed, 2012.

6

N

E W

S

168P/Hergenrother



Figure 2: Hergenrother’s projected path in the Western region of Andromeda: (23 Oct – 23 Nov) 2012!


6

N

E W

S

168P/Hergenrother

Alessi 22 (25 members & 82’ across)


The Professor Comet’s Report IAU MPC Ephemeris data for 168P/Hergenrother (25 Oct – 25 Nov) 2012:

All ephemeris data is calculated based on the Geographical location of

the George Observatory, SE Texas, United States.

29˚22’30” N, 95˚35’37” W

8

Date CDT/CST R.A. (J2000) Decl. Delta r El. Ph. M1* % Fore. Sky Motion Moon Phase Moon Mag. h m s "/min P.A. (0.00 – 1.00) (Visual) 2012 10 25 000000 23 42 50.3 +33 45 38 0.518 1.439 142.1 25.1 9.82 58 1.03 339.1 0.81 -11.84

2012 10 26 000000 23 42 17.4 +34 08 25 0.524 1.441 141.3 25.5 9.88 57 0.98 340.4 0.88 -11.99

2012 10 27 000000 23 41 48.5 +34 30 20 0.530 1.443 140.6 25.9 9.94 56 0.93 341.8 0.94 -12.10

2012 10 28 000000 23 41 23.7 +34 51 25 0.536 1.445 139.8 26.3 10.00 56 0.89 343.4 0.98 -12.17

2012 10 29 000000 23 41 03.0 +35 11 42 0.543 1.448 139.1 26.7 10.07 55 0.84 345.1 1.00 -12.20

2012 10 30 000000 23 40 46.4 +35 31 12 0.549 1.450 138.4 27.0 10.14 55 0.80 347.0 1.00 -12.19

2012 10 31 000000 23 40 33.8 +35 49 57 0.556 1.453 137.7 27.4 10.21 54 0.77 349.1 0.98 -12.15

2012 11 01 000000 23 40 25.3 +36 07 58 0.562 1.455 137.1 27.7 10.28 54 0.73 351.4 0.95 -12.08

2012 11 02 000000 23 40 20.9 +36 25 17 0.569 1.458 136.4 28.0 10.35 53 0.70 353.9 0.90 -11.97

2012 11 03 000000 23 40 20.6 +36 41 56 0.576 1.461 135.7 28.3 10.43 53 0.67 356.6 0.84 -11.83

2012 11 04 000000 23 40 24.2 +36 57 56 0.583 1.463 135.1 28.6 10.51 52 0.64 359.6 0.76 -11.67

2012 11 05 000000 23 40 31.9 +37 13 19 0.590 1.466 134.5 28.8 10.57 52 0.61 002.7 0.68 -11.46

2012 11 06 000000 23 40 43.6 +37 28 05 0.597 1.469 133.9 29.1 10.65 51 0.59 006.1 0.58 -11.21

2012 11 07 000000 23 40 59.2 +37 42 18 0.604 1.472 133.3 29.3 10.73 51 0.57 009.7 0.48 -10.90

2012 11 08 000000 23 41 18.7 +37 55 57 0.611 1.475 132.7 29.6 10.80 51 0.56 013.4 0.38 -10.52

2012 11 09 000000 23 41 42.2 +38 09 04 0.619 1.479 132.1 29.8 10.89 50 0.54 017.2 0.28 -10.02 2012 11 10 000000 23 42 09.4 +38 21 41 0.626 1.482 131.5 30.0 10.98 50 0.53 021.2 0.19 -9.36 2012 11 11 000000 23 42 40.5 +38 33 50 0.634 1.485 131.0 30.2 11.06 50 0.53 025.1 0.11 -8.44 2012 11 12 000000 23 43 15.4 +38 45 30 0.642 1.489 130.4 30.4 11.14 49 0.52 029.0 0.04 -7.00 2012 11 13 000000 23 43 54.0 +38 56 44 0.650 1.492 129.9 30.6 11.24 49 0.52 032.9 0.01 -4.09 2012 11 14 000000 23 44 36.2 +39 07 33 0.657 1.496 129.4 30.7 11.31 49 0.53 036.6 0.00 -1.77 2012 11 15 000000 23 45 22.1 +39 17 59 0.665 1.499 128.9 30.9 11.41 49 0.53 040.2 0.02 -6.30 2012 11 16 000000 23 46 11.6 +39 28 01 0.674 1.503 128.4 31.1 11.49 48 0.54 043.5 0.08 -8.08 2012 11 17 000000 23 47 04.6 +39 37 42 0.682 1.507 127.9 31.2 11.59 48 0.55 046.7 0.15 -9.17 2012 11 18 000000 23 48 01.0 +39 47 02 0.690 1.510 127.4 31.3 11.68 48 0.56 049.7 0.25 -9.92 2012 11 19 000000 23 49 00.7 +39 56 02 0.698 1.514 126.9 31.5 11.76 48 0.57 052.4 0.35 -10.48 2012 11 20 000000 23 50 03.8 +40 04 44 0.707 1.518 126.4 31.6 11.85 48 0.59 054.9 0.46 -10.90 2012 11 21 000000 23 51 10.1 +40 13 08 0.715 1.522 125.9 31.7 11.95 47 0.60 057.3 0.56 -11.23 2012 11 22 000000 23 52 19.5 +40 21 15 0.724 1.526 125.5 31.8 12.04 47 0.61 059.4 0.66 -11.50 2012 11 23 000000 23 53 32.0 +40 29 05 0.733 1.530 125.0 31.9 12.14 47 0.63 061.4 0.76 -11.71 2012 11 24 000000 23 54 47.6 +40 36 40 0.741 1.535 124.6 32.0 12.23 47 0.64 063.2 0.83 -11.88 2012 11 25 000000 23 56 06.0 +40 44 00 0.750 1.539 124.1 32.1 12.34 47 0.66 064.9 0.90 -12.01

(First Observation – 5 Sept 2012) *M1 = 5.5 + 5 log (delta) + 60.0 log r (6 Sept – 1 Oct) 2012 *M1 = -64.5 + 5 log (delta) + 500 log r (2 Oct 2012 – Present) *M1 = 1.8 + 5 log (delta) + 60.0 log r



The is a chart showing the change in apparent magnitude extrapolated

from a variety of visual observations taken from early September thru

late October with future predictions taken through 1 Feb 2013!

The ref. distance shows the change in distance of the comet with respect

to both the Earth & the Sun in A.Us!

9

Basic Definitions:

Perigee – Closest Distance to Earth

Apogee – Furthest Distance from Earth

Perihelion – Closest Distance to the Sun

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.008.00

11.00

14.00

17.00

20.00

23.00

Date (MM/DD/YYYY)

Re

f. Dista

nce

(A.U

.) A

pp

are

nt

Ma

gn

itu

de

(M

1)

(M1)Normalized Data Earth Distance Solar Distance

Perigee @ 0.423 AU (24 – 27) Sept 2012

Perihelion @ 1.415 AU (29 Sept – 6 Oct) 2012

Peak M1 Value (9.00) 2 Oct 2012



Figure 3: The projected path of the PanSTARRS comet across the Summer Sky (June 2011 – March 2013)!

Courtesy of Seiichi Yoshida’s Comet Page, 2012.

6

N

E W

S

C/2011 L4 PanSTARRS


Projected Path for C/2011 L4 PanSTARRS

C/2011 L4 PanSTARRS performing retrograde effect

(July 2011 – October 2012)

Positions for Maximum brightness

M1 predicted to be -1 (10 – 11) Mar 2013!

Solar Elongation: ~15˚

SUN


Figure 4: Projected path of C/2012 S1 (ISON) with an expected retrograde repeat: (1 March 2012 – 1 July 2013)!

6

N

E W

S

C/2012 S1 (ISON)




Figure 5: ‘Up Close’ retrograde path of C/2012 S1 (ISON) (30 June 2012 – 15 Aug 2013)!

6

N

E W

S

C/2012 S1 (ISON)



The project path of ISON during this retrograde sequence occurs during the time period from

Nov 2012 thru Jan 2013!

Northern arc of the retrograde motion as the comet moves from E to W during the same time

period contain the predicted positions where ISON is expected to reach it’s peak brightness!

Castor

Pullox

Mebsuta Jīxīn (Pile of Firewood)

Earth’s Shadow


Figure 6: An overlap of the paths of both comets: (Mid October – Mid November) 2012!

6

N

E W

S

C/2012 J1(Catalina) & 168P/Hergenrother



The project path of ISON during this retrograde sequence occurs during the time period from

Nov 2012 thru Jan 2013!

Northern arc of the retrograde motion as the comet moves from E to W during the same time

period contain the predicted positions where ISON is expected to reach it’s peak brightness!

168P/Hergenrother’s northward path

towards Andromeda!

C/2012 J1 (Catalina) Southward path into the ‘Great Square’ of

Pegasus!

Point of intersection for the trajectories of both

comets! (RA: 23h 40m 17.4s) (Dec: +35˚ 50’ 56”)


Overview of the Orbital Differences for Comets!

15

Comet Garradd is the perfect example of a non – periodic comet! The path is hyperbolic in nature. Comet 45P/Honda – Mrkos – Pajdusakova however is the perfect example of a periodic comet which is elliptical in nature.

Figures 6.1 & 6.2 are of Comet C/Garradd 2009 P1 and Figure 6.3 below is off 45P.

All images were obtained from the JPL Solar System Dynamics/Small Body Database Browser .

Courtesy of NASA/JPL/CalTech

Figure 6.1 Figure 6.2

Figure 6.3

P – Periodic Comets

C – Non Periodic Comets

Mid Autumnal Season Late Oct/Late Nov 2012

The Professor Comet’s Report 16 Fainter Predominant Comets for

Mid Autumn 2012

LINEAR C/2011 F1

(19 August 2012)

© Michael Jager

Catalina C/2012 J1

(18 August 2012)

©Michael Jager

LINEAR C/2012 K5

(19 August 2012)

©Michael Jager

LINEAR C/2011 UF305

(28 August 2012)

© Michael Jager Mid Autumnal Season – Late Oct/Late Nov 2012

The Professor Comet’s Report 17

PanSTARRS C/2011 L4

(7 August 2012)

© Chris Wyatt

McNaught C/2011 R1

(17 December 2011)

©Jose Francisco Hernandez

260P/McNaught C/2012 K2

(17 September 2012)

©Michael Jager Mid Autumnal Season – Late Oct/Late Nov 2012

Fainter Predominant Comets for

Mid Autumn 2012

the professor comet’s report 1 - north houston astronomy...

Documents