[BAA Comets] Comet Photometry

[David Storey]

Hi Denis,
         What photometry results are we aiming for here. MPC reports
generated by Astrometrica define N magnitudes. Is this what we need BAA CCD
observers to report to ICQ. Or do we need to establish a programme where the
whole coma is taken into account to derive a magnitude as appears to be
happening on the COBS web site. There is a link to the photometry packages
they use (DAOPHOT II for PCs, FitsPro ) but my computer will not display
those pages. The whole area of making CCD photometry of comets needs looking
at to establish what computer program is needed to get good data. I
personally don't know of a program that does full photometry of comet coma's
other than what I have read on the COBS site. Does anyone else of one that
is readily available?

Best Regards

Dave Storey

-----Original Message-----
From: comets-disc-bounces at britastro.org
[mailto:comets-disc-bounces at britastro.org] On Behalf Of denis buczynski
Sent: 17 September 2012 20:14
To: BAA Comets discussion list
Subject: Re: [BAA Comets] Comet Photometry

The reporting of photometric data to Jon or COBS is the procedure at the
very end of the process, and hopefully the COBS web based interface which
finally compiles the data into ICQ format will solve the problem for Jon.
That is why I pointed out the link in my initial post on this subject. 
However before we get to the reporting we need to have a discussion about
how the Section and it's members are advised to make those photometric
measurements. In essence we need to define a well thought out Section
Programme with details as to how we want members to participate. My concern
is that we are starting to discuss this procedure from the end rather than
the beginning. Let us firstly decide the nuts and bolts of the observing
programme and then move onto the reporting of results when we are content
with operation of the observing programme. We need a discussion about the
merits of alternative programmes and then choose a route which we all
support and can offer to our members. Once the observations and measurements
are made and the Section programme and procedures are followed, then the
reporting will normally be undertaken in line with the recommendations of
the programme. When observers use Astrometrica for the astrometry they
submit to MPC they report in the format of the programme, they don't then go
off and use a different format. 
This should be the case for the BAA Comet Photometry Programme(whatever that
might be), this is what we need to establish firstly.
Denis Buczynski


-----Original Message-----
From: Roger Dymock
Sent: Monday, September 17, 2012 7:44 PM
To: 'BAA Comets discussion list'
Subject: Re: [BAA Comets] Comet Photometry

The MPC format is for reporting both astrometry and photometry (of asteroids
and comets). In recent times they have got quite hot on the accuracy of
photometrc data.


Asteroid lightcurve data does use a different, ALCDEF, format - see
http://minorplanetcenter.net/light_curve

Agree on the need for a web interface to make life easier for the Director
and anyone else who wishes to access and analyse the data so, as mentioned,
will investigate COBS.

Regards

Roger Dymock
Email: roger.dymock at ntlworld.com
Tel: 023 92647986
Skype: rjvdymock
MPC Observatory Code: 940

-----Original Message-----
From: comets-disc-bounces at britastro.org
[mailto:comets-disc-bounces at britastro.org] On Behalf Of Shanklin, Jonathan
D.
Sent: 17 September 2012 18:27
To: BAA Comets discussion list
Subject: Re: [BAA Comets] Comet Photometry

The MPC format is for reporting astrometry, and the magnitudes reported
there are approximate with no metadata.  If you report photometry different
information is required.  As an analogy you wouldn't report the position of
a new variable star in the same format that you submitted a magnitude
estimate.

I agree it would be helpful to have only one format for reporting visual
observations, and would be quite happy if only the ICQ format was used
(Roger didn't mention many of the other formats - eg Morris, CBAT etc).  The
BAA format is only marginally different to the ICQ one, but many reports
received don't quite match either format and so need a lot of editing.  A
decent web interface that allows quick and simple input and thence
transmission to the Director would be a great help.

Regards, Jon

Director Comet Section, British Astronomical Association
http://www.ast.cam.ac.uk/~jds


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