The variable star charts on these pages are primarily intended for visual use. However, it is hoped that by linking the charts to the sequence files, CCD observers will find them useful also.

The basic properties of all the charts are the same. They all contain the star name, position, type, magnitude range, (if known), and a comparison star sequence. The labeled values of the comp stars are rounded to the nearest tenth of a magnitude, with the decimals omitted to avoid confusing them with stars.

All coordinates are equinox 2000.

The file nomenclature identifies the scale and orientation of the field on the chart.
C charts are drawn on DSS images, 15' field of view
B charts are drawn using Guide 8 and USNO A2.0, ~1/2 degree to 1/3 degree FOV
A charts are drawn using Guide 8 and USNO A2.0, ~ 1 degree FOV
North up charts are drawn with north up and west to the right
Standard charts are drawn with south up and east to the right
Reverse charts are drawn with north up and east to the right

All the charts are dated yymmdd to aid in keeping track of updates and revisions.
A and B charts are dated when the charts are drawn or revised.
C charts are dated with the same date as appears in the sequence file. This is a check for CCD observers to be sure they are using the corresponding charts and sequences.

These charts have been drawn using photometric information supplied by Arne Henden, US Naval Observatory Flagstaff Station. The majority of these sequences have been selected and documented in text format by Bruce Sumner. The remainder, were done by the author.

The sequence files contain the number of photometric observations, positions, magnitude, color information and errors for the comparison stars, and notes.

These charts are drawn as finder charts for stars that currently do not have accurate photometric calibration of the fields. The preliminary sequences are selected from USNO A2.0 information as a temporary measure until more suitable photometry becomes available.

The sequences are not documented as text files for these stars.

These charts will be based on photometric information supplied by Arne Henden and the TASS Mark IV camera, which will be included in an upcoming release of UCAC.

Current plans include charts for hundreds of LPVs, EBs and RR Lyrae stars.

The sequences for these stars will be documented in the same format as the Henden Sequences.

The guidelines used to select these sequences were established by the International Chart Working Group in July 2002.

It is important to emphasize that these are guidelines, not absolute rules. Each sequence is considered on a case by case basis.

1. Utilize photometry that is accurate to at least 0.05 only.
   0.05 being the standard for a visual chart; 0.02 the standard for a CCD chart.
2. CCD charts should be linked to the complete sequence information via the web.
3. Utilize comparisons of known color only. (B-V, or its equivalent in the sequence color index)
4. Choose comp stars that range between 0.3<B-V<1.0 , (or its equivalent in the sequence color index), with a conscious effort to limit the range to ~0.7.
5. Steps between comp stars should be between 0.3 and 0.5 throughout the range of the variable.
6. No redundant or duplicate values.
7. Exclude close doubles as comp stars.
8. Identify close companions to the variable as comp stars (if possible), to aid in identification.
9. Choose comp stars as close to the variable as possible. As a general rule, the fainter the comp star the closer to the variable.
10. Avoid large spatial distances between comps in the same magnitude range.
11. For visual charts, take position angle effect into account. Endeavor to pick comps along a line running E and W of the variable if there is a choice.
12. Tycho-2 data can be used to 10.5V. However, each star must be weighed on its own merits for errors.

When revising existing sequences there are additional guidelines.

- Utilize as many of the comparisons from previous versions of the sequence as are appropriate.
- Eliminate redundancies and duplications
- Eliminate red stars
- Eliminate variables
- Eliminate close doubles

Acknowledgements

I would like to thank the following individuals and organizations for supplying data, materials, general information, money, time and encouragement.

Arne Henden
Bruce Sumner
AAVSO
CDS
STScI
Steve Greene
Richard Huziak
Michael Koppelman
Vance Petriew
Joe Van Poucker
Irene Simonsen
Robert Stine
Dan Taylor
Steve Wolfe

Mike Simonsen  October 24, 2002