Call for Observations of HS 1804+6753

(from vsnet 527, Tom Marsh, Feb. 7)

Dear Colleagues,

a few months back I put out a message about an eclipsing dwarf nova called HS 1804+6753. I now have passed the first hurdle in getting time on this object on the Hubble Space Telescope. I am in the process of submitting the second phase of the proposal. An important component of this is the stage of acquiring the object which is done automatically by HST. There are two possibilities. The first uses a binary search algorithm and is fairly fast. The other slews the telescope about in a raster scan and is slow. However the first can fail on variable objects, and the target brightness must be known within +/- 1 magnitude.

Obviously outbursts can cause problems, but HS 1804+6753 has rather low amplitude outbursts and so I may be OK. What I would very much like to know is the range of magnitudes that anyone has observed for this star (excluding the eclipse). I would be very grateful for any data on this that anyone has. I am interested in V mags, but any colour (B-V) information would also be much appreciated.


Tom Marsh (e-mail: )

Dr. T.R. Marsh                     E-mail:
University of Southampton          Telephone: (44)-01703-592063 
Department of Physics              Fax:       (44)-01703-593910
Highfield                          WWW http:/
Southampton SO17 1BJ, England      ftp:

WWW link to:

Request for observations of HS1804+6753

vsnet 751, 1996 Aug. 20)

The Hubble Space Telescope is scheduled to observe the eclipsing dwarf nova HS1804+6754 on the 13 Sept. It will take high time-resolution space ultraviolet spectra more or less throughout the interval 03:19 to 15:07.

Any observations of this star would be useful. In particular magnitudes in the days leading up to and after the HST observations would be useful to establish the outburst state of this star.

During the HST observations themselves high speed photometry/spectroscopy would be of most use in extending the wavelength range covered.

Please let me know if you obtain any data,


Tom Marsh

Latest light curve from VSNET observations

Light curve

HS 1804+6753 page

(vsnet 759)

Dear Colleagues,

last week I sent around a message asking for ground-based observations in support of a Hubble Space Telescope program I have to look at the Northern eclipsing dwarf nova, HS 1804+6753. I have now set up a Web page with all the information on this program that observers would need (I hope). The address is

This include gif images of finding charts, coordinates, its ephemeris, a description of the the program and when it is due to run. Everything is fairly fixed now, but I will update the page if necessary.

If you are interested in observing this object, but cannot access the Web page, please send me an e-mail,


Tom Marsh

Previous Information on HS 1804+6753

HS1804+6753 page

Finding chart

Eclipse light curve obtained at Ouda Station (near outburst maximum, vertical scale represents differential V magnitudes)

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