The Bright EGRET Sources
The following objects have been detected by the Compton satellite and appear in the Third EGRET Catalog (3EG). The EGRET Catalog consists of sources consistently detected at energies E > 100 MeV. These particular gamma-ray sources have been identified with optical sources that are known as either BL Lac objects (BLL) or quasars (QSO). Some of these objects are well known and have a long history of variability. For other objects on this list, variability has not yet been reported. It is generally assumed that all AGNs are variable on some level, at least on the order of years or even months. BL Lac objects are the primary class of Optically Violent Variables (OVV) which can change in brightness unpredictably by 2-4 magnitudes or more in a matter of months.
|
|
|
|
variability |
|
|
|
|
|
BLL |
15.5 |
. |
02 22 39.6 |
+43 02 08 |
3C 66A |
|
|
BLL |
15.5 |
yes |
02 38 38.9 |
+16 36 59 |
|
|
|
BLL |
14.17 |
. |
07 21 53.4 |
+71 20 36 |
PKS 0716+714 |
|
BLL |
14.85 |
yes |
07 38 07.4 |
+17 42 19 |
OI 158 |
|
|
|
BLL |
14.0 |
yes |
08 54 48.8 |
+20 06 30 |
OJ 287 |
|
|
BLL |
13.5 |
yes |
11 04 27.3 |
+38 12 31 |
Mrk 421 |
|
|
QSO |
15.6 |
. |
11 59 31.8 |
+29 14 44 |
4C 29.45 |
|
|
QSO |
12.86 |
yes |
12 29 6.6 |
+02 03 08 |
3C 273 |
|
|
BLL |
14.5 |
yes |
22 02 43.2 |
+42 16 40 |
BL Lac |
The links in the above table on the 3EG designations are to finding charts based on POSS survey images. The finding charts are centered on the designated object and are slightly less than 15 arcminutes on a side. North is up and east is toward the left. These charts can contain objects as faint as 20th magnitude.
Links are also provided here to photometric sequences in these AGN fields. These sequences consist of finding charts with the sequence stars identified and values provided for BVR (and sometimes I). The sequence charts are typically 10 arcminutes on a side. These sequences are taken from the database maintained by the Extragalactic Astrophysics Group at the University of Heidelberg.
Several optical identifications have been made for sources of TeV photons detected using atmospheric Cherenkov telescopes. All of these sources appear to be AGNs of the blazar class (BL Lac types). The identified objects are Mrk 421, Mrk 501, and 1ES 2344+514. Of these sources, only Mrk 421 appears in the EGRET catalog. However, since AGN are notoriously variable, the other two TeV sources may have been in a low state during the Compton satellite mission. Since the remaining TeV sources are moderately bright, they are included here as gamma-ray loud AGN surveillance targets.
|
|
|
|
variability |
|
|
|
|
|
BLL |
13.8 |
yes |
16 53 52.1 |
+39 45 36 |
UGC 10599 |
|
|
BLL |
12 ? |
yes |
23 47 04.8 |
+51 42 18 |
The links on the target names are to POSS images which can be used as finding charts. The target is in the center of the images and the images are approximately 15 arcminutes on a side.
The sequence links are for finding charts and photometric sequences in the fields of these objects. The finding charts are approximately 10 arcminutes on a side.
[ top of page ]
