CCD Observing Manual

6.0 Observing Techniques

6.1 Using Star Charts

The AAVSO has thousands of variable star charts available and new ones consistently being released. These charts have been continuously produced since the organization was founded in 1911. As such, the types and quality of the charts differ depending on when they were made. In general, all charts are intended as visual observing charts with errors to .1 visual accuracy. When CCD observing with these charts, use a V filter since V comes closest to the way things look visually. Record your observation to .1 accuracy.

Beginning in 2000, the AAVSO began publishing f-scale charts with data on them intended for CCD observers. These "CCD tables" usually included more details on the sequence used on the chart for visual observers. With these details (usually more accurately magnitude values and color indices) CCD observers can attempt to make estimates more accurately and in more color.

An example of one of these tables is seen to the right. The data from the table mostly comes from the source cited in the "Sequence:" field of the chart, located at the bottom of the image. However, this data can change. It can be revised or (more likely) improved by the astronomer who made the measurements. So be sure to consult the sequence source for the latest sequence data if you intend to work on a project that requires the most precise photometric data possible.

• Click here for a list of charts with a CCD table

Sometimes there may not be a chart available for an object you want to observe. It is possible to choose your own comparison stars. However, there is no single published photometric database of faint stars all over the sky. Most of the faint catalogs out there (USNOA/B, GSC2, etc.) are very poor at photometry and cannot be relied upon. So what to do? In a pinch take an image of the field in a red and a blue filter. Look for comparison stars that are slightly brighter than the variable and that look like they have the same color. Then use a USNOB magnitude for that comparison star. Be sure to use the TO comment code in your observation report, which tells us that you did not use an AAVSO chart. Then put the USNOA2 ID of the star in the Comments Explained field. If you plan on doing lots of observations of this star, contact charts@aavso.org and the chart team will try to make you a proper chart or at least ID a good comparison star for you to use.

6.2 Reporting Observations to the AAVSO

The AAVSO receives over 400,000 observations per year. Most of those are visual observations of just a few observations per star. CCD observers, however, can sometimes generate thousands of observations of one object per night. Submitting those one-by-one can be a problem so we have created special upload tools for CCD observers.

Method 2: Batch Upload

If you have large amounts of data to upload, such as time series observations, then you should use the WebObs first.

The CCD Batch Upload Tool currently supports the formats made by AIP4Win, CBA, MaximDL and a generic 2 column format easily created with spread sheet programs.

Comment Codes, Comp Stars, & Charts

When you submit observations made with a CCD camera be sure to include the proper information about the filter used. If you did not use a filter put CCD in the Comment Codes field. For V use CCDV, B: CCDB, R: CCDR, I: CCDI, U: CCDU, and Z-band: CCDZ

Also be sure to list your comparison stars ("comp stars") and the chart you used. This is especially important for CCD observers since your data can be very precise. If you are using a chart made by yourself or another organization put K in the Comment Codes field.

• More information on the Official AAVSO Format

Note: Tools such as WebObs and PCObs do the formatting for you so you don't have to know the Official AAVSO Format.

6.3 Using the MyNewsFlash System

The MyNewsFlash is a completely customizable and automated system to have variable star observations sent to you. It is a way to monitor your favorite stars or classes of stars and/or to be notified when something interesting is in outburst. The staff sometimes e-mails Special MyNewsFlashes when a specific object needs extra attention.

When starting out we recommend just to signup with all the default options checked. This will send you an e-mail once a day of CV's in outburst and all Special MyNewsFlash issues (usually ~1 per month). Then you can always go back and create more profiles or tweak yours to add new objects to the list.

6.4 Using the Special Notice

6.5 Using CCD Views

CCD Views is a publication of the AAVSO CCD Committee. Its goal is to provide CCD observers with observing program ideas, hints and tips to make observing more fun and productive, and to provide feedback on observations submitted. CCD Views also routinely accepts submitted articles from AAVSO members and observers. It is a good general publication to read for ideas and background information. If you have specific questions about anything in CCD views send it to the AAVSO or post it to the AAVSO Photometry Discussion Group.

CCD Views is distributed when circumstances warrant via the Web site and e-mail.