(vsnet-alert 345, Peter Kroll)

SS LMi fading from unobserved outburst ?

Sweeping through stars listed in Tonny Vanmunster's poorly studied CVs I found SS LMi beeing significantly brighter than its normal brightness of [21p (see "The complete TOAD list" of Steve Howell: but not at its maximum brightness of about 15p.

Using a 60-cm-Cassegrain equipped with a CCD camera at Sonneberg Observatory I could measure in B,V and R band. Linking to the finding chart at the Cataclysmics Home P@ge ( the object was about 18.5+/-0.3 in V (1996 Feb. 26.2). It is difficult to get reliable magnitudes since the GSC magnitudes given in the finding chart cannot be regarded as very accurate. Owing to the measurements in B and in R, the object seems to be bluish. I will try to link these magnitudes to calibrated stars within the next clear nights.

Unfortunately, the weather at the last night (Feb. 26/27) was too poor to find the star. And during this night (Feb. 27/28) the moon did its job to flood every exposure and I could'nt find the star again. So I wonder if somebody else could be able to find and measure this star during the very next days (nights).

I am also not absolutely sure that I catched the right star. Tonny Vanmunster's GSC finding chart indicates the position only roughly, if we take into account that the object is 21mag normally. The fainter the limit the more stars might be the right candidate. About 2 arc min to the west appears another (reddish) star of about 18.5/19th magnitude, but its position deviates slightly from that in the finding chart.

Given that identification and measurements are correct, the question arises, if SS LMi has had an unobserved outburst in the last days or weeks, or if its normal state is brighter than 21 mag. I have checked observations of SS LMi mainly made by T.Vanmunster and G. Poyner, published in the last VSNET Circulars. These are all "fainter than" observations with a limit of about 15. SS LMi is listed with 15p-[21p. Perhaps we did not notice former outbursts with a maximum brightness not reaching that height?

Best regards, Peter Kroll

| Dr. Peter Kroll      |                      |
+----------------------+ Sternwarte Sonneberg |     S O N N E B E R G
| Tel. (49) 3675 81214 | Sternwartestr. 32    |
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Recent SS LMi observations

(vsnet-alert 346, T. Kato)

Though I am not completely sure whether the "right" SS LMi is being observed, every occasions (a few times in the past several years) I found an image of a star (V~18 or 19) very near the reported position in the Duerbeck's atlas (1987 Space Sci. Rev. 45, 1), which showed a blank field in POSS.

I have put a finding chart down to V=18.5 in the VSNET Home Page (, under "Whats's new" or "Topics"; a GIF image may be also obtained via VSNET anonymous ftp under DNe/SS_LMi) based on a CCD image taken on 1996 Jan. 1, which also showed a star at the same position. Unfortunately the object was not automatically measured when making a chart, so the approximate position of the variable was taken from Duerbeck 1987, which may be different from that of the detected image by a few arcseconds. I hope this would help.

There has been at least one additional ocassion when the object was positively observed (reported in IAUC by Howell, if I remember correctly). Although I am not perfectly confident of the identitiy of the object, my observations before and after Howell's observation showed a red persistent source roughly at the same magnitude as we are observing recently. From these observations, it may be that SS LMi is not experiencing an outburst, but rather the object was anomalously faint when POSS plate was taken (before the discovery of a major brightening in 1980).

Clearly it is an urgent task to confirm the identity. We hope we can provide a CCD image (in GIF) through the VSNET Home Page and anonymous ftp.

Taichi Kato

V-band CCD image in 1996 Jan. (Ouda Station)

(exposure 480s, 1996 by T. Kato, Jan. 1)

Jan. 1 (240s)

Jan. 12 (150s) by D. Nogami

Jan. 12 (240s) by D. Nogami

Feb. 15 by H. Baba faded.

Comment by S. Howell

(vsnet-alert 347)

Report on SS LMi

I thought it might be useful to report on what I have discovered about SS LMi over the past few years. Duerbeck (1987) presents a description of the observation of the outburst in 1980 as well as a chart of the region with a circle at the best guess position.

Deep CCD images of the region show that within the circle there is indeed a star. It is a red object with a V magnitude near 21-22. On two occasions, seperated by about 1 year, I have obtained spectra of that star. The spectra were obtained with the MMT (arizona) and the WHT (La Palma) and both show identical results. The star within the circle in Duerbeck appears to be a late type M star, possibly a subgiant.

CCD time-series photometry of the SS LMi region has also be obtained on two occasions.

One was from Lowell Observatory, and consists of a number of short (1-2 hour long) time-series datasets, obtained during a partially cloudy week. The data were reduced and every star within the region near SS LMi (covering a ~ 5 arc min square and down to V~21), was measured. NO stars was found to be statistically variable, not even the star within the Duerbeck circle.

The other time-series data consists of two longer (about 4 hrs each), better data sets of the SS LMi region covering a larger field of view and going to V~22-22.5. They were obtained at the prime focus of the La Palma INT. These are currently undergoing reduction.

So to date, there is NO evidence that the star within the Duerbeck circle is a CV at all, and NO evidence of any nearby star being a variable. So data obtained during this outburst or brightening is indeed important as the true identity of the SS LMi candidate object is currently unknown.

Steve Howell

 Planetary Science Institute, Astrophysics Group 
 620 N. 6th Ave. 
 Tucson, AZ 85705  USA 
 Phone (520) 622-6300 
 Fax (520) 622-8060 

VSNET chart

in VSNET format

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