AAVSO HOME > publications > alert notice
AAVSO Alert Notice 353

Monitoring of Blazars requested for VERITAS/XMM TOO
July 11, 2007

Our assistance has been requested by Dr. Markus Boettcher, Ohio University, in a study he and colleagues are making of several blazars. The targets are being intermittently monitored by VERITAS (the Very Energetic Radiation Imaging Telescope Array System), a four-telescope collection designed to detect astrophysical sources of very high energy (VHE) gamma-rays that is located at the Fred Lawrence Whipple Observatory in Arizona. If a VHE gamma-ray outburst is detected by VERITAS, target-of-opportunity observations with the Newton X-ray Multi-Mirror (XMM) telescope will be triggered. Since VERITAS is not regularly monitoring the targets, optical monitoring is crucial to alert the VERITAS collaboration to a high state of any one of the blazars on the list in order to initiate VERITAS observations.

The XMM observing season has begun, so AAVSO observers are requested to monitor the target blazars from now through at least May 2008, when the current XMM observing cycle ends. Dr. Boettcher and colleagues have submitted a Chandra proposal along the same lines that, if funded, would extend the study throughout most of 2008.

The target list is given below. Finder charts for nine of the ten targets are available through VSP (http://www.aavso.org/observing/charts/vsp), but two of these do not have sequences. Also, the sequences for three targets are not completely available in VSP right now but are available through pre-existing AAVSO charts, so please follow the URLs given for these stars. The tenth target does not have either a finder chart or a sequence available right now.

NAME             DESIG     AAVSO NAME  RA (2000.0) DEC (2000.0)  MAG

Sequence available in VSP:

1. 1ES0033+595   0030+59   1ES0033+59  00:35:52.63 +59:50:04.6   19.5V
2. 1ES0806+524   0802+52   1ES0806+52  08:09:49.19 +52:18:58.4   14.84V
3. MRK 1218      0832+25   MRK 1218    08:38:10.95 +24:53:42.92  16.3V
4. 1ES1627+402   1625+40   1ES1627+40  16:29:01.31 +40:07:59.9   19V
Comp star coordinates in VSP and values plotted on chart, but magnitudes
not in VSP photometry table yet (sequence photometry available at URLs given
after each star):
5. 3C 66A        0216+42   3C 66A      02:22:39.61 +43:02:07.80 ~13.7-15.7V
6. BL LAC        2158+41   BL LAC      22:02:43.29 +42:16:39.98 ~13.0-15.5V
use 'f' scale chart at
Sequence temporarily not in VSP; please go to URL below for chart and sequence:
7. W COM         1216+28   W COM       12:21:31.69 +28:13:58.50 ~12.9-15.8V
No sequence available in VSP:
8. 1ES0120+340   0117+33   1ES0120+34  01:23:08.9  +34:20:50     15.2V
9. 1ES0647+250   0644+25   1ES0647+25  06:50:46.6  +25:03:00     15.8V
No chart or sequence available (to be announced when added to VSP):
10.1H 0323+342   0318+33   1H0323+342  03:24:41.16 +34:10:45.86  15.72V

Dr. Boettcher has requested the following hierarchy of observations: Cousins R nightly or multiple times per night; add B if possible; one UBVRI set per night if possible; signal-to-noise ratio of 50 or better.

VERITAS uses R-band threshold magnitudes to trigger observations. The table below contains the threshold R magnitude for each target as well as an approximate V-magnitude trigger value. If you observe a target at or brighter than the threshold, please notify AAVSO Headquarters immediately by submitting your observation via WebObs. If the target is below the threshold, please try to submit your observation within 24 hours. The astronomers need to be alerted within one to two days, and we have to allow time for confirmation, so please do not delay in reducing your data and submitting your observations.

    Object        |AAVSO Name   | R_{trigger} | ~ V_{trigger}
1.  1ES 0033+595  |1ES0033+59   | 14.5        | 14.9
2.  1ES 0806+524  |1ES0806+52   | 14.5        | 14.9
3.  MRK 1218      |MRK 1218     | 12.5        | 12.9
4.  1ES 1627+402  |1ES1627+40   | 16.5        | 16.9
5.  3C 66A        |3C 66A       | 13.7        | 14.1
6.  BL LAC        |BL LAC       | 12.8        | 13.2
7.  W COM         |W COM        | 13.7        | 14.1
8.  1ES 0120+340  |1ES0120+34   | 14.4        | 14.8
9.  1ES 0647+250  |1ES0647+25   | 14.0        | 14.4
10. 1H 0323+342   |1H0323+342   | 15.0        | 15.4

The campaign will be coordinated at the AAVSO by Dr. Matthew Templeton, AAVSO staff astronomer (by Elizabeth Waagen July 14-19).

Your observations will be crucial to the success of this exciting campaign. Many thanks for your observing efforts and valuable contributions. Good observing!

Elizabeth O. Waagen, Senior Technical Assistant


Information on submitting observations to the AAVSO may be found at:



An Alert Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL: