Elusive Mercury

Hi all,
I have been checking the western horizon region more than normal for
Mercury as I had posted on how to find it. I hoped that I was would be lucky
enough to catch a view of it and I succeeded tonight at 8 30 BST. The sky
was like it has been for the last 4 nights here in South Yorkshire i.e.
parallel layers of cloud to the horizon with only small clear breaks in them
on the western horizon. But I got lucky after about 5 minutes and saw Venus
and straight away then Mercury. The sighting only lasted for about 10
seconds and then the clouds took over again. Hope some more of you managed
to get a sighting of Mercury.

Mercury fades from -0.7 magnitude on 3rd April by about 0.1 magnitude each
following night until the 8th April when it is only -0.1 magnitude so it is
much fainter and harder in the evening glare to find as the week progresses,
so do try and hope for a break in the clouds. Using my old school day
mathematics I come to the value of it being 1.78 times fainter on 8th April
than on 3rd April if anybody can verify this values accuracy I would be most
grateful.

In uk.sci.astronomy message , Sat,
3 Apr 2010 21:05:15, CJ posted:

Mercury fades from -0.7 magnitude on 3rd April by about 0.1 magnitude
each following night until the 8th April when it is only -0.1 magnitude
so it is much fainter and harder in the evening glare to find as the
week progresses, so do try and hope for a break in the clouds. Using my
old school day mathematics I come to the value of it being 1.78 times
fainter on 8th April than on 3rd April if anybody can verify this
values accuracy I would be most grateful.


Five days @ 0.1 mag/day = 0.5 mag. 5 mag = *100. 100^0.1 = 1.581. But
you did say "about".

Check
http://www.heavens-above.com/planets...ng=-0.9&loc=Ho
me&alt=0&tz=GMT daily for magnitudes.

Where on the Web is an authoritative and precise definition of Magnitude
1.0 ? And, for that matter, Mag diff 5.0 = factor of 100 ? (I've read
the newsgroup FAQ.)

Mercury was very visible from here, just outside SW London, near 20:30
BST today - local lighting notwithstanding. Clearly the ancients would
have had no difficulty in recognising it as a planet.

--
(c) John Stockton, nr London, UK. Turnpike v6.05 MIME.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

"Dr J R Stockton" wrote in message
nvalid...
In uk.sci.astronomy message , Sat,
3 Apr 2010 21:05:15, CJ posted:

Mercury fades from -0.7 magnitude on 3rd April by about 0.1 magnitude
each following night until the 8th April when it is only -0.1 magnitude
so it is much fainter and harder in the evening glare to find as the
week progresses, so do try and hope for a break in the clouds. Using my
old school day mathematics I come to the value of it being 1.78 times
fainter on 8th April than on 3rd April if anybody can verify this
values accuracy I would be most grateful.


Five days @ 0.1 mag/day = 0.5 mag. 5 mag = *100. 100^0.1 = 1.581. But
you did say "about".

Check
http://www.heavens-above.com/planets...ng=-0.9&loc=Ho
me&alt=0&tz=GMT daily for magnitudes.

Where on the Web is an authoritative and precise definition of Magnitude
1.0 ? And, for that matter, Mag diff 5.0 = factor of 100 ? (I've read
the newsgroup FAQ.)

Mercury was very visible from here, just outside SW London, near 20:30
BST today - local lighting notwithstanding. Clearly the ancients would
have had no difficulty in recognising it as a planet.

--
(c) John Stockton, nr London, UK. Turnpike v6.05
MIME.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms &
links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm,
etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail
News.

Sorry I was not more precise but I did say that it faded by 0.6 magnitudes
from April 3rd to April 8th. The formula I used was from Norton's Star
Atlas which gives magnitude m is follows

m=2.5 log 100 which means for log 100 being 2 then the magnitude difference
is 2.5 times 2 which equals 5. This was introduced by Pogson around 1850
(again from Norton's). So substituting 0.6 for log 100 in the formula I came
up with 0.6/2.5 which is 0.24 so it is 1.74 times fainter and not 1.78 as
in my original posting. The figure normally used to define 1 magnitude
difference is 2.512 which using this comes out at 100.0226 brightness
difference for 5 magnitudes, so the correct figure is slightly less than
2.512 (I do not have tables to say what this value is to a better accuracy).

Finally glad that you managed to spot Mercury even from SW London, I live
on the main A628 on the edge of Barnsley South Yorkshire and I have to cope
with sodium lighting glare also.

If you spot Venus and are unable to see Mercury it will be visible in any
decent binoculars just to the right of Venus. Position Venus to the left
hand side of the field of view and Mercury is then easily found. I tried
this at 8 15 pm BST on Monday when Mercury was lost to naked eye view until
8 26 pm BST.

On 03/04/2010 21:05, CJ wrote:
Hi all,
I have been checking the western horizon region more than normal for
Mercury as I had posted on how to find it. I hoped that I was would be
lucky enough to catch a view of it and I succeeded tonight at 8 30 BST.
The sky was like it has been for the last 4 nights here in South
Yorkshire i.e. parallel layers of cloud to the horizon with only small
clear breaks in them on the western horizon. But I got lucky after about
5 minutes and saw Venus and straight away then Mercury. The sighting
only lasted for about 10 seconds and then the clouds took over again.
Hope some more of you managed to get a sighting of Mercury.


I saw Mercury tonight, Wed, 7th April around 9pm. I'm 67 and have never,
consciously anyway, seen it before.

It was clearly visible to the naked eye and looked very bright in 10x50
bins. It was to the right of Venus and, as described, at the opposite
edge of the field of view. I hastily set up my 4.5 inch reflector but
couldn't see any more than through the bins - no crescents or gibbous
shapes.

I live 15 miles east of Stoke-on-Trent and looking towards Stoke is not
usually rewarding because of the lights; although I saw Mercury, I
didn't see any stars!

Another Dave

"Another Dave" wrote in message
...

I saw Mercury tonight, Wed, 7th April around 9pm. I'm 67 and have never,
consciously anyway, seen it before.

Well done! As the man said, it's knowing where to look!

It's been rather cloudy around here, but I must remember to have a look if
the sky's clear enough.

I got a really good view of Mercury 3 years ago -
http://www.flickr.com/photos/allybeag/383108137/

ally

In uk.sci.astronomy message , Wed,
7 Apr 2010 12:53:18, CJ posted:
The figure normally used to define 1 magnitude difference is 2.512
which using this comes out at 100.0226 brightness difference for 5
magnitudes, so the correct figure is slightly less than 2.512 (I do not
have tables to say what this value is to a better accuracy).

You post with header
X-Newsreader: Microsoft Windows Live Mail 14.0.8089.726
so probably have access to Windows.

Windows calculator, View scientific, 100 x^y 0.2 = gives
2.5118864315095801110850320677993 . As a check,

promptlongcalc 25118864315095801110850320677993 5 pow wrt

gives (longcalc via sig line 3) (newlines added by hand)

LONGCALC: www.merlyn.demon.co.uk = 2005-07-22
compiled with Borland Delphi.
+9,999,999,999,999,999,999,999,999,999,999,454,709 ,453,133,245,614,349,
411,082,264,035,106,045,642,732,476,557,243,271,69 5,040,665,903,248,533,
615,979,717,781,043,389,731,050,409,257,121,938,69 4,263,619,373,193

and, as a check, I did the 'pow' with base-13 arithmetic too,

so Windows calculator cannot be far out.



Finally glad that you managed to spot Mercury even from SW London,

Seen also tonight.

--
(c) John Stockton, nr London UK. DOS 3.3, 6.20; WinXP.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links.
PAS EXE TXT ZIP via URL:http://www.merlyn.demon.co.uk/programs/00index.htm
My DOS URL:http://www.merlyn.demon.co.uk/batfiles.htm - also batprogs.htm.

"Dr J R Stockton" wrote in message
nvalid...
In uk.sci.astronomy message , Wed,
7 Apr 2010 12:53:18, CJ posted:
The figure normally used to define 1 magnitude difference is 2.512
which using this comes out at 100.0226 brightness difference for 5
magnitudes, so the correct figure is slightly less than 2.512 (I do not
have tables to say what this value is to a better accuracy).

You post with header
X-Newsreader: Microsoft Windows Live Mail 14.0.8089.726
so probably have access to Windows.

Windows calculator, View scientific, 100 x^y 0.2 = gives
2.5118864315095801110850320677993 . As a check,

promptlongcalc 25118864315095801110850320677993 5 pow wrt

gives (longcalc via sig line 3) (newlines added by hand)

LONGCALC: www.merlyn.demon.co.uk = 2005-07-22
compiled with Borland Delphi.
+9,999,999,999,999,999,999,999,999,999,999,454,709 ,453,133,245,614,349,
411,082,264,035,106,045,642,732,476,557,243,271,69 5,040,665,903,248,533,
615,979,717,781,043,389,731,050,409,257,121,938,69 4,263,619,373,193

and, as a check, I did the 'pow' with base-13 arithmetic too,

so Windows calculator cannot be far out.



Finally glad that you managed to spot Mercury even from SW London,

Seen also tonight.

--
(c) John Stockton, nr London UK. DOS 3.3, 6.20;
WinXP.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms &
links.
PAS EXE TXT ZIP via
URL:http://www.merlyn.demon.co.uk/programs/00index.htm
My DOS URL:http://www.merlyn.demon.co.uk/batfiles.htm - also
batprogs.htm.

I never realised that Windows calculator had all those other functions. So
instead of fumbling around with log, sine, tan, and cosine tables I can now
work much quicker and more accuracy than I do.

It amazing that by sharing information with others how it invariably has a
positive effect to your own advantage.

I also tried to get an image of Venus and Mercury using my video camera last
night. The jury is out on whether I caught Mercury as there are speckles in
the image but probably I got Mercury too.