Mercury Transit on May 09, 2016

Unlike the Venus transit which is a rare event, there is a Mercury transit every 7.5 years (on average). Between 1601 and 2400, there are only 14 Venus transit. If you have not seen the last one on June 06, 2012, it is too late  since the next Venus transit occurs on Dec 11, 2117 !! Therefore, we should focus on the Mercury transit.

The next transit of mercury occurs on May 09, 2016. It starts at about 11:12 UT and ends on 18:42 UT. The transit is visible in most of Asia, Europe, Africa, and America. Note that the apparent size of the solar disk is about half a degree while the apparent size of mercury disk is only 8 arc seconds (1 degree = 60 arc minute = 3600 arc second).

The next mercury transits in this century are the followings (time in UT):

Date                    start           max          end

Nov  13, 2032      06:41         08:54      11:07

Nov 07, 2039       07:17         08:46       10:15

May 07, 2049       11:03         14:24       17:44

Nov 09, 2052       23:53         02:29       05:06

May 10, 2062       18:16         21:36       00:57

Nov 11, 2065        17:24         20:06      22:48

Nov 14, 2078        11:42         13:41      15:39

Nov 07, 2085        11:42         13:34      15:26

May 08, 2095        17:20         21:05      00:50

Nov 10, 2098        04:35         07:16      09:57

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Losmandy G11 mount

I have used the famous Losmandy G-11 mount for a few years. It is a super heavy mount. You need quiet a bit of force to move it around. The mount was serviced recently and with a rough polar alignment, it allowed us to have exposures of up to five minutes at a focal length of 300 mm.

close-up view of Losmandy G-11 mount.

The Losmandy G-11 mount.

The ball head to connect DSLR cameras.

The ball head allows you to point the camera to any direction of the sky very easily. Depending on the weight of the camera and lens, you should think of a ball which has a diameter of at least 30-40mm for a 5 kg load.

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Questar 8 inch

Questar 8 inch (old) telescope and the Losmandy G-11 mount.

The above image shows preparation for an observing session after a busy observing day. The telescope was pretty old but good enough to see the Venus-Jupiter conjuction on June 30, 2015.

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Comet ISON revisited (Oct 01, 2013)

In an earlier post a while ago, I discussed about possibility to have a very bright comet this November/December. The updates are mostly disappointing as comet ISON does not perform the best expected. Alan Mac Robert from Sky and Telescope reviews the status of this comet recently and provided realistic estimated for expected brightening:

It can still be cached by small telescopes. However, the chance of having a bright (naked-eye) comet like Hale-Bopp is not significant.

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Comet C/2012 S1: a dream comet?

Discovered a few weeks ago, comet C/2012 S1  is predicted to be the brightest comet in the last few centuries ! Some people already called it a dream comet. I think many people still remember spectacular shows of Comet Hyakutake and  Hale-Bop. I have observed both when I was a bachelor student. But this new comet is predicted to be shortly as bright as full Moon. In the nearest distance to the Earth, it will be about 0.4 AU away from us, comparable to the great comet of 1680.

The great comet of 1680

However, I am concerned if we can ever watch this comet that spectacular. The nearest passage on 28 November 2013, it has a distance of about 1.8 million kilometers from the solar center (twice of the great comet of 1680). Considering the solar radius of about 695,000 km, that means it will be at a distance of about two solar radii from the solar surface. It is well “in” the solar corona.. Well, sungrazing comets survive even closer distance from the sun in perihelion. Lets see  if it can survive this dramatic passage.

NASA JPL predicted the following ephemeris for this comet. The table lists the date, right ascension and declination, as well as the apparent visual magnitude of the comet:

*************************************************************
Date                             R.A.             DEC                      MAG
*************************************************************
2012-Oct-01      08 16 15.64    +27 48 11.7           17.98
2012-Nov-01     08 21 30.69   +28 07 20.5           17.44
2012-Dec-01     08 14 29.76    +29 10 23.0           16.87
2013-Jan-01     07 51 24.41    +30 43 46.2           16.30
2013-Feb-01     07 17 30.61    +31 43 49.6           15.84
2013-Mar-01    06 50 55.54    +31 32 54.6          15.54
2013-Apr-01     06 37 34.44    +30 34 47.7          15.23
2013-May-01    06 41 38.71    +29 27 23.0         14.88
2013-Jun-01     06 59 16.67    +28 14 15.3          14.37
2013-Jul-01      07 25 33.62    +26 50 47.2         13.67
2013-Aug-01     07 59 58.82    +24 55 45.5         12.68
2013-Sep-01     08 41 49.95    +22 07 43.3         11.28
2013-Oct-01     09 34 32.27    +17 37 46.8          9.26
2013-Nov-01     11 12 17.58    +06 22 36.3         5.64
2013-Nov-01     11 12 17.58    +06 22 36.3         5.64
2013-Nov-11     12 16 17.67    -02 06 57.1          3.71
2013-Nov-21     14 02 19.97    -14 55 26.6         0.73
2013-Dec-01     16 19 20.89    -14 02 53.8          n.a.
2013-Dec-11     16 10 33.49    +05 18 36.2         1.42
2013-Dec-21     16 13 52.09    +31 55 14.6         2.76
2013-Dec-31     16 35 13.15    +67 12 33.9         3.89
2014-Jan-01     16 40 39.24    +70 35 30.0          4.02
2014-Feb-01     04 13 57.65    +57 18 56.9          8.07

Please note that the early prediction of comet brightness is usually uncertain due to various effects, e.g. the planetary tidal force causing new orbital parameters, fragmentation, etc. At the moment, the comet is so far away that there is no clear idea about the diameter of the comet nucleus. Hence, the super bright comet C/2012 S1 should be quoted with care. Indeed, JPL quoted that the orbit is probably very poorly determined. I hope it will be at least visible to the naked eye.

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