[BAA Comets] Data for next week (2012 S1)

[Graham Relf]

On 26/11/2013 15:56, Graham Relf wrote:
> On 26/11/2013 14:14, Roger Dymock wrote:
>> Hi Graham,
>>
>> At http://britastro.org/computing/applets_ecliptic.html it would 
>> appear that I have the option of
>> one comet or all of them which makes the chart a little crowded. 
>> Would it be possible to include a
>> magnitude filter so that only those comets which are within the range 
>> of the observer's equipment
>> are shown? For example I might want to choose brighter than mag 10 if 
>> observing visually or perhaps
>> 14 if using a CCD camera.
>>
>> Regards
>>
>> Roger Dymock
>> Email: roger.dymock at ntlworld.com
>> Tel: 023 92647986
>> Skype: rogerdymock67 or
>> Skype: rjvdymock
>> MPC Observatory Code: 940
>> Project Alcock http://www.britastro.org/projectalcock/
>>
>>
>> -----Original Message-----
>> From: comets-disc-bounces at britastro.org 
>> [mailto:comets-disc-bounces at britastro.org] On Behalf Of
>> Graham Relf
>> Sent: 25 November 2013 15:29
>> To: BAA Comets discussion list
>> Subject: Re: [BAA Comets] Data for next week (2012 S1)
>>
>> On 25/11/2013 14:21, Shanklin, Jonathan D. wrote:
>>> Hi Graham,
>>>
>>> I had a quick look, and seems fine.  I'm preparing a talk for 
>>> tomorrow about comets, and looked at
>> the latest chart for 2013 R1.  Unfortunately the stars shown are 10 - 
>> 11 mag, when the comet is 5 -
>> 6 mag.  The what's observable page also insisted on downloading the 
>> latest java, which was a bit
>> annoying as I've already  got java running.  It then locked up 
>> firefox which was even more annoying.
>> The page shows 273P/Pons-Gambart (not visible) but not 2013 R1 
>> (brightest visible comet), and it
>> isn't on the list of objects to add either.
>>> Regards, Jonathan Shanklin
>>>
>>> Director Comet Section, British Astronomical Association
>>> http://www.ast.cam.ac.uk/~jds
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>> Jonathan,
>>
>> Yes, I have rather left the old What's Observable page behind because it
>> causes so many problems now that Java has been made so awkward. Despite
>> the fact that we have not finished testing it and there are some known
>> glitches, you'll be better off with the new version at
>> http://britastro.org/computing/applets_ecliptic.html which does show all
>> the latest comets.
>>
>> I should really switch the links so the new page is the first one people
>> get to. Sorry to have caused you bother.
>>
>> Regards,
>> Graham
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> Roger,
>
> You have a point, and a useful suggestion. Estimated comet magnitudes 
> are of course dubious though! And we may not have data for estimating 
> all of them. I'll see what we can do.
>
> Regards,
> Graham
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I was also asked about the convention for measuring azimuth. There are 
different standards for azimuth but I follow Jean Meeus (see his 
Astronomical Algorithms, 2nd edition, p91). He admits that astronomers 
do not all agree but he measures azimuth from the South, positive 
Westwards, because that is the way hour angle is measured, at least for 
observers in the northern hemisphere.

One reason I included azimuth in the tables is that I have suggested to 
my local photo society that they might like to get up early too (!). By 
looking at a local map they may be able to position themselves to 
photograph the comet alongside a landmark.

Graham