2 2009 Fermi Symposium, Washington, D.C., Nov. 2-5 3. VERITAS Blazar KSP 5. VERITAS AGN Detections 5.1. Recent VERITAS Blazar Discoveries 4. Blazar Discovery Program eConf C091122 Prior to the launch of Fermi VERITAS had discov- ered VHE emission from 2 blazars. These included the first VHE-detected IBL, W Comae [14, 15], and the HBL 1ES 0806+524 [16]. VERITAS has discov- ered 6 VHE blazars since the launch of Fermi. Three of these were initially observed by VERITAS prior to the release of Fermi-LAT results, due to the X-ray brightness of the synchrotron peaks of their SEDs. VHE emission from 3C 66A was discovered by VER- ITAS in September 2008 [17] during a flaring episode that was also observed by the Fermi-LAT [18]. The observed flux above 200 GeV was 6% of the Crab Neb- ula flux and the measured VHE spectrum was very soft (Γ VHE ∼ 4 . 1). RGB J0710+591 was detected The blazars observed in the discovery program are largely high-frequency-peaked BL Lac objects. How- ever, the program also includes IBLs (intermediate- peaked) and LBLs (low-peaked), as well as flat spec- trum radio quasars (FSRQs), in an attempt to in- crease the types of blazars known to emit VHE γ -rays. The observed targets are drawn from a target list con- taining objects visible to the telescopes at reasonable zenith angles ( − 8 ◦ < δ < 72 ◦ ), without a previously published VHE limit below 1.5% Crab, and with a measured redshift z < 0 . 3. To further the study of the VERITAS has detected VHE γ -ray emission from 16 AGN (15 blazars), including 8 VHE discoveries. These AGN are shown in Table I, and each has been detected by the Large Area Telescope (LAT) instru- ment aboard the Fermi Gamma-ray Space Telescope. Every blazar discovered by VERITAS was the sub- ject of ToO MWL observations to enable modeling of its simultaneously-measured SED. The known VHE blazars detected by VERITAS were similarly the tar- gets of MWL observations. EBL a few objects having a large ( z > 0 . 3) are also included in the target list. The target list includes: VERITAS observes for ∼ 750 h and ∼ 250 h each year during periods of astronomical darkness and par- tial moonlight, respectively. The moonlight observa- tions are almost exclusively used for a blazar discovery program, and a large fraction of the dark time is used for the blazar KSP, which consists of: • A VHE blazar discovery program ( ∼ 200 h / yr): Each year ∼ 10 targets are selected to receive ∼ 10 h of observations each during astronomi- cal darkness. These data are supplemented by discovery observations during periods of partial moonlight. • A target-of-opportunity (ToO) observation pro- gram ( ∼ 50 h / yr): VERITAS blazar obser- vations can be triggered by either a VERI- TAS blazar discovery, a VHE flaring alert ( > 2 Crab) from the blazar monitoring program of the Whipple 10-m telescope or from another VHE instrument, or a lower-energy flaring alert (optical, X-ray or Fermi-LAT). Should the guar- anteed allocation be exhausted, further time can be requested from a pool of director’s discre- tionary time. • Multi-wavelength (MWL) studies of VHE blazars ( ∼ 50 h / yr + ToO): Each year one blazar receives a deep exposure in a pre-planned campaign of extensive, simultaneous MWL (X- ray, optical, radio) measurements. ToO observa- tion proposals for MWL measurements are also submitted to lower-energy observatories (e.g. Swift) and are triggered by a VERITAS discov- ery or flaring alert. • Distant VHE blazar studies to constrain the ex- tragalactic background light (EBL): Here dis- tant targets are given a higher priority in the blazar discovery program, as well as for the MWL observations of known VHE blazars, par- ticularly those with hard VHE spectra. • All nearby ( z < 0 . 3) HBL and IBL recom- mended as potential VHE emitters in [5, 6, 7]. • The X-ray brightest HBL ( z < 0 . 3) in the recent Sedentary [8] and ROXA [9] surveys. • Four distant ( z > 0 . 3) BL Lac objects recom- mended by [5, 10]. • Several FSRQ recommended as potential VHE emitters in [6, 11]. • All nearby ( z < 0 . 3) blazars detected by EGRET [12]. • All nearby ( z < 0 . 3) blazars contained in the Fermi-LAT Bright AGN Sample [13]. • All sources ( | b | > 10 ◦ ) detected by Fermi-LAT where extrapolations of their MeV-GeV γ -ray spectrum (including EBL absorption; assuming z = 0.3 if the redshift is unknown) indicates a possible VERITAS detection in less than 20 h. This criteria is the focus of the 2009-10 VERI- TAS blazar discovery program.