[vsnet-alert 10346] ATEL 1622 ROTSE3 candidate CV images in HADP and MEGAPRIME

bydra at Safe-mail.net bydra at Safe-mail.net
Sat Jul 19 23:07:26 JST 2008

Using Aladin it can be found that images of the object ROTSE3 J004626+410714 can be found in MegaPrime taken with CFHT on 2004-11-12, with SDSS u, g and r images having been taken within half an hour of each other, roughly, and with SDSS i and z passband images taken about 9 days later.

The object is evidently in a bright state in the u, g and r images, with u and g visually looking not too disimilar in magnitude upon the images, but r being markedly fainter.  The object had either markedly faded by the time the i and z images were taken later, or there was a strong colour difference.

I don't really know how to use Sextractor fully, but given the noted fits image zeropoint of about 26th mag for the g image, and a Sextractor noted isomag of -9 or so, it was likely around 16th to 17th mag at that time.

The Heidelberg Digitized Astronomical Plates server


also has archival images of the field.

The A prefixed plates from a search in that form give some mixed depth images, of varying limiting magnitude.

However, using some field stars as comparators for this object it can be see that for plate

A699-1900-08-28 M31

on August 28th 1900 the object was clearly shown, but a similar depth image

A339-1990-06-29 M31

on June 29th 1990 does not show it.

Again a similar depth of field A341-1990-07-04 M31 about a week later does not appear to show, possibly.

It is undetected again in late August (A354), barely detected in late November 1992, and seen in 1996, but not particularly at its brightest.

Variation does not seem to be gradual, and likely more fits erratic variation, but the sampling is very sparse and uneven.

However, the field is a busy one in the CHFT images, the r and z images looking extended, and with a very faint object just 1.5" North, amongst other very faint field stars.

This work used CDS Aladin, images from the CHFT MegaPrime archive, data from the Heidelberg Digitized Astronomical Plates service, and the UK Astrogrid's Astroscope image, spectra and catalogue archive interrogator (might as well use it whilst it's still there, seeing as the fundings been totally pulled, which leaves me to wondering how the UK is going to remain part of VO).



John Greaves

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