Variable-Star Observing

Variable-star observing offers the chance to contribute real science without the need for huge investments of time and money. It is fun to do and a great way to learn about the night sky and about stars in particular. There are very few objects in the night sky that are as dynamic as variable stars, which is what attracts many observers to this interesting aspect of astronomy.

Observing From Northern Latitudes

For observers who take up variable-star observations, there are a number of variable stars particularly suitable for observation from Canada. If you have access to a good observing location with a clear view of the northern sky, as close to the horizon as possible, then you have an opportunity to measure variable stars throughout the entire year. This is particularly useful in variable-star astronomy, where observations throughout the entire cycle of variability are preferred. The further north you are the better, since more stars will become circumpolar and will therefore be available for observation year round. Even stars at their most northerly point, on the meridian below Polaris, can be visible earlier in the evening or during the early morning hours, as the the Earth's rotation carries them 180 degrees or more around the northern horizon.

Canadian Variable-Star Observing Mentors

Canada has several expert variable star observers who would be glad to help new variable star enthusiasts get started in this important work. We encourage you to contact the following observers if you need some assistance or if you would just like to get to know others in the field to create a sense of community.

• Richard Huziak of the Saskatoon, Saskatchewan Centre of the RASC.
  email - Rick Huziak
• Patrick Abbott of the Edmonton, Alberta Centre of the RASC.
  email - Patrick Abbott
• Bob Nelson of the Prince George, British Columbia Centre of the RASC.
  email - Bob Nelson
• Geoff Gaherty of the Toronto, Ontario Centre of the RASC.
  email - Geoff Gaherty
• Christopher Beckett, Chair of the RASC Observing Committee.
  email - Christopher Beckett

Visual Observing

By far the largest category in the AAVSO database, the visual observing program covers about 5,000 stars mainly from the Pulsating and Eruptive classes. Most of them are large-amplitude stars (variations of one magnitude or more) that are suitable for accurate visual studies. The Pulsating category includes Long-Period Variables, Semi-Regulars, R Coronae Borealis types, as well as Cepheids and Symbiotic stars. The Eruptive category includes Novae, Recurring Novae, Dwarf Novae, Supernovae, and a few others. More information about these can be found on our introductory page, and you can find several charts for a wide variety of variable stars on our Sample Charts One and Sample Charts Two pages.

Nova Search

If you like the thought of discovering an important astronomical event, then this program is for you. Since the 1930s, the AAVSO has been organizing systematic searches of the Milky Way looking for "new" stars or for stars that have become brighter than normal. These discoveries are usually Novae or Recurrent Novae that flare up within our galaxy from time to time. Several notable discoveries have occurred due to the perseverance of AAVSO observers over the last 70 years or more, and you can be sure that it will happen again! For this program, regions of the sky are divided up into sections of 10 degrees in Declination by 1 hour in Right Ascension (except around the poles where this is modified somewhat), so that each observer can cover one area specifically. By concentrating on one area, an observer becomes very familiar with the star patterns and magnitudes of its constituent objects and therefore should be able to readily notice anything unusual. Sky Atlas 2000, The AAVSO Variable Star Atlas, and other well-known star atlases can provide a good reference tool for the stars in each region. A list of the Nova Search Regions of the night sky can be found on the AAVSO Web sites.

Supernova Search

Similar to the Nova Search Program, but much more challenging, is the Supernova Search Program. Since supernovae are rare occurrences in our own galaxy, astronomers have to look into distant galaxies to find these elusive, but fascinating and important objects for study. Peering into galaxies millions of light-years away can be done either visually or by the use of imaging equipment. For visual searches, an observer has to become very knowledgeable about the normal appearance of his or her target galaxies, so that they can accurately identify any "new" stars that may appear in those areas. This involves obtaining images of those galaxies and using them for comparison to the current view through the eyepiece of a telescope. A supernova searcher also needs to be aware that objects such as asteroids and comets can appear similar to a supernova when they are passing though the search area. It is recommended to anyone who is interested in this type of activity to obtain a good planetarium software program such as The Earth Centered Universe and a quality observing guide such as the RASC Observer's Handbook, in order to keep track of the positions of known asteroids and comets within the magnitude range of your search instrument. It is also wise to check key Web sites that post information about any new objects that have come into view in the night sky. More information about supernovae and the various search methods of the AAVSO Supernova Search Committee can be found on their Web site.

Eclipsing Binaries

The AAVSO has a dedicated committee that overlooks the eclipsing-binary program, and the program incorporates both visual and electronic imaging methods. Visual measurements are still a large part of the program, but photoelectric and CCD-imaging methods are becoming increasingly more popular. For many eclipsing binaries, visual and electronic measurements complement each other and both are needed. Reporting methods for the eclipsing-binary program are different than for the general visual observing program; for instance observations have to be sent in on 8.5 x 11 sheets of paper once a month, and individual observation times are recorded using Universal Time (UT) without converting it to the Julian Date (JD). Several detailed Eclipsing Binary Star Charts are available at the AAVSO Web site. Our own Bob Nelson of the Prince George Centre is an expert in regards to Eclipsing Binary Stars; you can contact him at bob.nelson@shaw.ca

RR Lyrae

RR Lyrae stars require very accurate observations and therefore are best left for eagle-eyed observers who like a challenge. These stars also require regular monitoring and may be more suitable for observers who live in relatively cloud-free locations like Arizona, USA. Having said that, though, RR Lyrae stars are so interesting that you will probably want to check them out to observe their incredibly short periods of variability. These stars can go through an entire cycle from minimum to maximum and back again in just few hours, or within the time frame of one observing session. You can find RR Lyrae Charts at the AAVSO is available on their Web pages.