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Walter's LogBook |
| DO Draconis Dazzles and Amazes! |
The variable DO Draconis (1137+72) is a U Geminorum type star located about 10 degrees east of M81 and 82, and less than 3 degrees from lambda Draconis. I have been following it for a couple of years and wondered if it would ever do anything! Night after night it would just sit there at magnitude 14-15. Then around September 20th, it went into outburst!
The AAVSO email News Flash (No. 499) announced the outburst on September 21st. According to the AAVSO International Database this star's most recent outburst occurred in mid-October 1996, when the star reached a mean visual magnitude of 10.4 (announced in News Flash No. 231). Prior to that, DO previous had an outburst in September 1990 with a maximum magnitude of 9.7 (as announced in No. 68). In between (1990-1996), DO had had several minor brightenings reaching between magnitude 14.0 and 14.5.
Below are the observations reported in the News Flash, along with my own (not reported in the News Flash):
| DATE (UT) | Magnitude | AAVSO Observer Initials |
| SEP 13.838 | <15.0 | PYG |
| SEP 17.823 | <13.7 | MUY |
| SEP 18.81 | <13.5 | SPK |
| SEP 19.8951 | <14.3 | (me) |
| SEP 20.830 | 11.2 | MUY |
| SEP 20.9035 | 11.0 | WDM |
| SEP 21.142 | 10.7 | SPK |
| SEP 22.8611 | 11.4 | (me) |
| SEP 23.8903 | 12.0 | (me) |
| SEP 26.8889 | <13.2 | (me) |
You can see that the star does not stay "up" very long! My last observation (on Sept. 26) was done with a full moon in the sky and was very difficult, but I just had to know what DO was doing (or should that be DOing?)!
Interestingly, the AAVSO chart for DO Draconis also lists it as YY Draconis. This is good because my LX200 returns a "No matching object..." message when I try to go to DO Draconis (star #340137), but it will go to YY Draconis (star #340052). AAVSO member John Isles was kind enough to tell me the details of how this strange situation arose:
The object originally designated YY Dra was an eclipsing binary with range 12.9 to below 14.5 photographic and period 4.21123 days. Unfortunately this object is lost. There is no star like this near the co-ordinates published by the 1934 discoverer, W. Zessewitsch. Probably there was a large error in the reported position.
When a long-cycle dwarf nova was later found very close to the published position of YY Dra, it was at first assumed to be the same object, and for a time observers called it YY Dra. Then the Moscow team that names variable stars decided the dwarf nova was really a different object, and gave it the new designation DO Dra. You should therefore call it DO Dra in your reports.
I don't know why your LX200 doesn't find DO Dra, but possibly its database includes only the variables in the 1985 edition of the General Catalogue of Variable Stars, whose listing for Draco ended at DN.
When will DO Draconis go into outburst again? The only way to know for sure is to keep watching!