[Aavso-photometry] Re: [cvnet-discussion] VV is one lonely Pup!

Fri Feb 11 09:03:09 EST 2005

Can someone help me out? Why does an equatorial location lead to star
trailing for exposures longer than 30 sec with "commercial type"
telescopes? This isn't true as far as I know unless by "commercial type"
one means alt-az mount. 

-----Original Message-----
From: aavso-photometry-bounces at mira.aavso.org
[mailto:aavso-photometry-bounces at mira.aavso.org] On Behalf Of Berto
Monard
Sent: Friday, February 11, 2005 4:51 AM
To: aavso-photometry at aavso.org; aaronp at onceler.org
Cc: cvnet-discussion at yahoogroups.com
Subject: [Aavso-photometry] Re: [cvnet-discussion] VV is one lonely Pup!

Dear Aaron,

Recent 'unfiltered' observations show VV pup evolving around 17.5CR. I
wonder if, at this faint level, any precise timeseries photometry via
filtered observations can be done by the usual amateur instrumentation.

But if VV Pup is a polar, it will give a reasonably good signal over the
unfiltered CCD band while measurements in the different bands will
likely show a similar light curve. 

At decl -19, VV Pup is very much equatorial, which means that longer
exposures (more than 30 sec) will produce significant star trailing on
most of the images with the commercal type telescopes. This will firmly
reduce the magnitude reach in filtered photometry.

If someone were (in addition to unfiltered runs, produced by others
perhaps) to make (by means of stackings) 'deep' snapshot observations in
the different filters, the overall information can still be had. From
past experience I am not a strong believer in the quality of timeseries
derived from stacked images...

I hope that Arne (in his capacity as expert astro-photometrist) has
comments on all this.

Good luck with the campaign. I will definitely apply a dense coverage
with snapshot observations, probably even with filters, weather
allowing.

Regards,

Berto Monard / #MLF

Bronberg Observatory / CBA Pretoria

>>> aaronp at onceler.org 10/02/2005 21:47:56 >>>

 Hey all. We really need CCD observations of VV Pup during the next
week. If you can observe it please make it your #1 priority target. We
have no recent data at all. Below is a copy/paste from the recent
announcement in CCD Views #330:

http://www.aavso.org/publications/ccdviews/330.shtml 

------------------------------------------------------------------------
---
3. VV PUP CAMPAIGN IN SUPPORT OF KECK OBSERVATIONS
Dr. Steve Howell, WIYN Observatory & NOAO, has requested observations of
the polar VV Pup to coincide with observations being done at the Keck
Observatory on February 16, 2005 (UT). Time series observations for as
long as possible in BVRI are requested from 00:00 UT February 15 - 23:00
UT February 17, 2005. VV Pup is quite faint and also near the quarter
Moon during the observing window. So we recommend the following
observing plan:

1) Observe it in one filter instead of alternating between filters. Set
your exposure time to get an SNR > 20. You may need to stack images to
reach this SNR.

2) Small and moderately sized telescopes should observe in Ic first and
in Rc if you don't have an Ic filter or someone else is currently
observing in Ic. This will lessen some of the effects of the Moon and
also lower exposure time (this is a field with heavy extinction). Those
with larger apertures should go for V and B photometry.

3) Post to the aavso-photometry discussion group and tell us what filter
you are using and the expected start and end time of your observation
run. This way someone else can use a different filter if they are
observing at the same time.

We currently have very few observations of VV Pup. So baseline
observations prior to and immediately after the observing campaign would
be very useful.

The AAVSO Chat Room will be open for this event! Join us during the
campaign at http://www.aavso.org/aavso/chat.shtml .

The VV Pup chart is here:
http://www.aavso.org/cgi-bin/searchcharts3.pl?name=vv%20pup 

Our observations of VV Pup are minuscule!! We desperately need some
photometry. Our latest observations of VV Pup: VV PUP JAN 01.4960 <15.3
SRX Visual VV PUP DEC 31.8280 17.2 CCD MLF Unfiltered VV PUP DEC 28.4424
16.305 CCDI CTX ERR: .03 VV PUP DEC 23.4785 18.38 CCDV CTX ERR: .027 SRX
- Rod Stubbing, Australia CTX - Tim Crawford, Oregon, USA MLF - Berto
Monard, South Africa 
------------------------------------------------------------------------
-
Aaron

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