Searching For Comet C/2011 L4 PANSTARRS

Expectations of the appearance of Comet C/2012 L4 PANSTARRS is running high since the first solution it’s orbit. Magnitudes are expected in the minus range, sporting a long broad tail after sunset. I’ve seen the preview of this picture before, withthe repeat to follow at the end of the year.

First item to consider is the comet will be close to the Sun and the horizon when it reaches peak brightness. The comet will slowly move from the southeast of the setting Sun, moving northward and gradually higher each night. It will share the twilight sky with a crescent Moon and later light of the First Quarter Moon.

And that’s a description of the path the comet will take. This all happens in mid March in North Eastern Pennsylvania, not the most forgiving of weather around here most of the time. Dark clouds silhouetted against a light blue sky, winds whipping from the west, and with snow on the ground or sub freezing temperature. The regional weather can hinder viewing this comet, do you recall looking for comet C/2006 P1 Mc Naught in January 2007? Searching the western horizon for the coma or tail between broken layers of clouds each night.

Comet Hale-Bopp came around in March and April of 1997, it was in the northern sky, farther from the setting Sun and moving towards the north west. Weather conditions cooperated that year, moderate temperature, no snow on the ground and many clear nights without clouds made for many clear views of Hale-Bopp. March weather the year before and the year after Hale-Bopp were more typical of the start of spring. Cloudy skies, cold temperature and snow on the ground.

C/2012 L4 PANSTARRS is moving in the opposite direction, hence it will be viewed in twilight skies for a while as it quickly sets before the sky becomes completely dark. To rub it in, Daylight Savings Time begins as the comet appears. Make any required adjustments to your computer, planetarium software, or computer controlled telescopes.

If you must travel to a location to get a good view of the western sky, then binoculars would be the first instrument to use when searching the twilight sky for C/2012 L4 PANSTARRS. A digital SLR camera or a Point and Shoot on a tripod will give results with exposure of less than 20 seconds for focal length of 50 mm. Take many pictures as the every changing twilight sky will affect the exposure time. This would be good practice for the next comet at the end of the year.

Use software to calibrate, if you also take Darks and Flat images,to process and to stack the individual images. The list of software to examine included, RegiStaX, Deep Sky Stacker both freeware. Photoshop, CCDStack, MaximDL are commercial software, the later two astrophotography packages.

Plan ahead if you are setting up a telescope to view or take pictures. If it is a computer controlled telescope mount then, you may need the use the Moon or Sun to fix the scope’s position before you can slew the telescope to the comet. Arrive early to set up and wait for the comet to appear.

Here are the position of the comet at 7:30 p.m. Eastern Daylight Time using a conservative magnitude estimate from Guide8 software. Remember the comet will be seen in a twilight sky, not against the dark night sky. Magnitudes will be difficult in a twilight sky, frustrating with moving clouds on the horizon.

Addition Jan 20, 2013

New magnitude estimate by Sechii Yoshida  put the comet at magnitude  2 or magnitude 3 at brightest.  http://www.aerith.net/comet/catalog/2011L4/2011L4.html

This reminds me of the appearance of comet Bradfield 1974 b (C/1974 C1) in March  1974.  Comet Bradfield  perihelon to the Sun was 0.5 AU,  higher in the sky at sunset and seen better as darkness fell. It traced a path in the western sky similar to what C/2012 L4 PANSTARRS will due this March. Comet Bradfiled reach 5 th magnitude back in 1974,  C/2012 L4 PANSTARRS will be closer to the horizon than comet Bradfield.

PANSTARRS (C/2011 L4) Magnitude listed are assumptions

Date                                    RA          declination       r     delta mag Elong Alt Azim    Sun el

—-                                       –             ———–          -       —–    —   —–  ——   ——     —–

9 Mar 2013 19:30:59 00h21m52.73s -05 34′ 33.2″ 0.3016 1.1092 0.5 15.2 4.31 258.73 -6.1

10 Mar 2013 19:30:59 00h25m12.39s -02 55′ 44.1″ 0.3026 1.1144 0.5 15.1 5.98 260.79 -5.9

11 Mar 2013 19:30:59 00h27m56.28s -00 19′ 00.0″ 0.3068 1.1203 0.6 15.2 7.51 262.95 -5.7

12 Mar 2013 19:30:59 00h30m07.40s +02 14′ 25.0″ 0.3141 1.1266 0.7 15.5 8.89 265.16 -5.5

13 Mar 2013 19:30:59 00h31m49.45s +04 43′ 33.4″ 0.3240 1.1333 0.9 15.8 10.13 267.43 -5.2

14 Mar 2013 19:30:59 00h33m06.40s +07 07′ 45.3″ 0.3364 1.1402 1.1 16.4 11.21 269.71 -5.0

15 Mar 2013 19:30:59 00h34m02.20s +09 26′ 37.9″ 0.3509 1.1474 1.3 17.0 12.17 271.99 -4.8

16 Mar 2013 19:30:59 00h34m40.49s +11 40′ 02.6″ 0.3671 1.1548 1.5 17.7 13.00 274.26 -4.6

17 Mar 2013 19:30:59 00h35m04.52s +13 48′ 01.7″ 0.3848 1.1624 1.7 18.5 13.72 276.51 -4.4

18 Mar 2013 19:30:59 00h35m17.06s +15 50′ 45.1″ 0.4035 1.1700 1.9 19.4 14.34 278.72 -4.2

19 Mar 2013 19:30:59 00h35m20.43s +17 48′ 27.1″ 0.4232 1.1778 2.1 20.3 14.87 280.90 -4.0

20 Mar 2013 19:30:59 00h35m16.52s +19 41′ 24.9″ 0.4436 1.1857 2.3 21.3 15.33 283.03 -3.8

21 Mar 2013 19:30:59 00h35m06.89s +21 29′ 56.8″ 0.4645 1.1936 2.6 22.2 15.73 285.11 -3.6

22 Mar 2013 19:30:59 00h34m52.77s +23 14′ 21.0″ 0.4858 1.2016 2.8 23.2 16.08 287.15 -3.4

23 Mar 2013 19:30:59 00h34m35.18s +24 54′ 55.5″ 0.5074 1.2097 3.0 24.2 16.38 289.14 -3.2

24 Mar 2013 19:30:59 00h34m14.90s +26 31′ 57.2″ 0.5293 1.2178 3.2 25.2 16.64 291.08 -3.0

25 Mar 2013 19:30:59 00h33m52.57s +28 05′ 42.1″ 0.5513 1.2259 3.4 26.2 16.87 292.98 -2.8

26 Mar 2013 19:30:59 00h33m28.70s +29 36′ 25.0″ 0.5734 1.2341 3.5 27.2 17.07 294.84 -2.6

27 Mar 2013 19:30:59 00h33m03.69s +31 04′ 19.6″ 0.5955 1.2423 3.7 28.2 17.25 296.65 -2.4

28 Mar 2013 19:30:59 00h32m37.84s +32 29′ 38.5″ 0.6176 1.2506 3.9 29.2 17.41 298.42 -2.2

29 Mar 2013 19:30:59 00h32m11.40s +33 52′ 33.4″ 0.6398 1.2588 4.1 30.2 17.56 300.15 -2.0

30 Mar 2013 19:30:59 00h31m44.55s +35 13′ 14.7″ 0.6619 1.2671 4.2 31.2 17.70 301.84 -1.8

31 Mar 2013 19:30:59 00h31m17.42s +36 31′ 52.2″ 0.6839 1.2754 4.4 32.2 17.84 303.50 -1.6

1 Apr 2013 19:30:59 00h30m50.13s +37 48′ 34.9″ 0.7058 1.2837 4.5 33.1 17.96 305.12 -1.4

2 Apr 2013 19:30:59 00h30m22.72s +39 03′ 30.9″ 0.7277 1.2920 4.7 34.1 18.09 306.71 -1.2

3 Apr 2013 19:30:59 00h29m55.23s +40 16′ 47.6″ 0.7495 1.3003 4.8 35.0 18.21 308.27 -1.0

4 Apr 2013 19:30:59 00h29m27.68s +41 28′ 32.0″ 0.7712 1.3086 5.0 36.0 18.34 309.80 -0.8

5 Apr 2013 19:30:59 00h29m00.05s +42 38′ 50.2″ 0.7927 1.3169 5.1 36.9 18.47 311.30 -0.6

6 Apr 2013 19:30:59 00h28m32.31s +43 47′ 48.1″ 0.8142 1.3251 5.2 37.8 18.60 312.77 -0.4

7 Apr 2013 19:30:59 00h28m04.42s +44 55′ 31.0″ 0.8355 1.3334 5.3 38.7 18.73 314.21 -0.2

8 Apr 2013 19:30:59 00h27m36.31s +46 02′ 03.6″ 0.8567 1.3417 5.5 39.6 18.88 315.63 0.0

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