GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"3296 results found.
- EP260822a: Einstein Probe detection of a fast X-ray transient
- The EP-WXT trigger 01709287395 is likely a flaring star
- GRB 260818B: SVOM/C-GFT optical upper limit
- EP260731a: SVOM/ECLAIRs detection through offline targeted search
- The EP-WXT trigger 01709286204 is likely a flaring star
- EP detected a brightening of LMXB 1ES 1735-26.9
- GRB 260818B: EP-FXT follow-up observation
- GRB 260818A: J-band observations with WINTER
- GRB260818A: EP-FXT follow-up observation
- EP260806a: SAO RAS multicolor optical observations
- EP260806a: SVOM/ECLAIRs detection through targeted search
- The EP-WXT trigger 01709281429 is likely a flaring star
- EP260812a: AZT-22 optical upper limit
- EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
- EP260806a: WFST optical observations
- The EP-WXT trigger 01709280562 is likely a flaring star
- EP260812b: Optical upper limit with Kinder
- The EP-WXT trigger 01709279838 is likely a flaring star
- EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
- EP260812a: SVOM/C-GFT optical upper limit
- EP260812b: SVOM/VT optical observation
- EP260812b: Einstein Probe detection of an X-ray transient
- EP trigger #01709278129 (EP260812b?): NOT optical counterpart
- EP260812a: Einstein Probe detection of an X-ray transient
- GRB 260809A: SAO RAS optical observations
- GRB 260808B: SAO RAS optical observations
- EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
- GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
- The EP-WXT trigger 01709278015 is likely a flaring star
- EP260809a: J-band upper limit with WINTER
- EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
- EP260809a: LCO optical observation
- GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
- EP260809a: Einstein Probe detection of an X-ray transient
- EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260806a: SVOM/VT optical observation
- EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
- EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260806a: LCO likely optical counterpart
- EP260806a: Einstein Probe detection of an X-ray transient
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- AT 2026wki: EP/FXT follow-up observations
- GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
- GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
- GRB 260802A: SVOM/VT optical upper limits from VHF data
- GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- The EP-WXT trigger 01709277420 is likely a flaring star
- GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
- GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
- EP260731a: COLIBRÍ optical upper limit
- EP260731a: NOT optical upper limit
- EP260731a: Einstein Probe detection of an X-ray transient
- EP260728a: COLIBRÍ optical upper limit
- EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
- The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
- EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
- EP260729a: Einstein Probe detection of an X-ray transient
- EP260727a: SAO RAS optical observations
- GRB 260727A: AbAO and SAO RAS optical observations
- EP260728a: EP-FXT follow-up observation
- GRB 260726A: EP-FXT follow-up observations
- EP260728a: Einstein Probe detection of a fast X-ray transient
- GRB 260727A: SVOM/GRM observation
- EP260727a:refined analysis of the EP-WXT and EP-FXT observation
- Konus-Wind detection of GRB 260727A
- EP260727a: NUTTELA-TAO Early Optical Limits
- GRB 260727A: EP/FXT follow-up observations
- EP260727a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
- EP260723a: SVOM/ECLAIRs Upper Limit
- EP260723a: further EP-FXT follow-up observation
- EP260725a: EP-FXT follow-up observation and association with a bright flaring star
- EP260725a: EP-WXT detection of an X-ray transient
- EP260723a: EP-FXT follow-up observation
- EP260723a: SVOM/VT optical observation
- EP260723a: NOT optical conterpart confirmation
- EP260723a: Liverpool Telescope likely optical counterpart
- EP260723a: EP-WXT detection of a fast X-ray transient
- Konus-Wind detection of GRB 260721A
- Konus-Wind detection of GRB 260714B
- GRB 260718A: EP-FXT follow-up observation
- GRB 260618B: EP-FXT follow-up observation upper limit
- EP260703a: SVOM/ECLAIRs Upper Limit
- GRB 260706A: ATCA detection of possible radio counterpart
- EP260713a: Einstein Probe detection of an X-ray transient
- GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
- EP260711a: EP-FXT follow-up observation
- EP260711a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
- EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
- GRB 260704A: SVOM/ECLAIRs refined analysis
- GRB 260706A : GRANDMA Upper limits
- GRB 260706A: Further EP-FXT follow-up observation
- GRB 260706A: SVOM/VT optical upper limits
- EP260707a (by EP-FXT): NOT optical upper limit
- EP260707a is not a real source
- EP260707a: LCOGT Optical Upper Limit
- EP260707a: TRT optical upper limit
- EP260707a: Einstein Probe detection of an X-ray transient
- GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate