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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.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
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"

27396 results found.

  1. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  2. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  3. EP250704a/GRB 250704B: 10 GHz VLA detection
  4. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  5. IceCube-250706A: No Candidates from WINTER
  6. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  7. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  8. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  9. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  10. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  11. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  12. EP250704a/GRB250704B : HCT optical and NIR upper limits
  13. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  14. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  15. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  16. GRB 250702F: radio detection with the VLA
  17. IceCube-250706A: EP-FXT follow-up observations
  18. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  19. GRB 250706B/C: Fermi-LAT detection
  20. IceCube-250706A: Global MASTER-Net observations report
  21. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  22. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  23. GRB 250706B: Swift/UVOT Detection
  24. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  25. GRB 250702F: GRANDMA observations
  26. GRB 250706A: Swift-XRT refined Analysis
  27. GRB 250706B: refined SVOM/MXT data analysis
  28. GRB 250706A: Swift/UVOT Upper Limits
  29. GRB 250706B: REM optical observations
  30. GRB 250706A: REM optical/NIR observations
  31. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  32. IceCube-250416A: DDOTI Optical Upper Limit
  33. IceCube-250706A: COLIBRÍ optical upper limits
  34. GRB 250706A: JinShan optical upper limits
  35. GRB 250706A: SAO RAS optical observations
  36. EP250704A: NOWT Detection
  37. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  38. GRB250706B: Swift-XRT counterpart detection
  39. GRB 250706B: iTelescope optical observations
  40. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  41. GRB 250706B: SVOM/VT optical observation
  42. GRB 250706B: TRT bright optical counterpart detection
  43. GRB 250706A: GROWTH-India Telescope optical upper limit
  44. GRB 250706B: SVOM detection of a long burst
  45. GRB 250706A: Swift detection of a burst
  46. GRB 250704B: Swift-XRT refined Analysis
  47. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  48. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  49. GRB 250703A: EIRSAT-1 GMOD Detection
  50. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  51. GRB 250704B: Swift/UVOT Upper Limits
  52. GRB 250704A: Swift/UVOT Detection
  53. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  54. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  55. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  56. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  57. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  58. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  59. GRB 250702F: Kilonova-Catcher optical afterglow detection
  60. GRB 250702F: Monte Agliale Observatory optical observations
  61. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  62. EP250704a / GRB 250704B: JinShan optical observations
  63. EP250704a / GRB 250704B: SAO RAS optical observations
  64. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  65. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  66. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  67. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  68. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  69. EP250704a / GRB250704B: Swift-XRT counterpart detection
  70. GRB 250704A: Swift-XRT afterglow detection
  71. EP250704a / GRB 250704B - REM observations
  72. GRB 250702F: GROWTH-India Telescope optical observations
  73. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  74. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  75. EP250702a: WFST optical observations
  76. EP250704a: COLIBRÍ optical counterpart candidate
  77. EP250704a: Einstein Probe detection of an X-ray transient
  78. GRB 250704A: REM detection of the optical afterglow
  79. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  80. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  81. GRB 250704A: SVOM detection of a burst
  82. GRB 250702F: Swift/UVOT Detection
  83. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  84. GRB 250702F: Swift-XRT refined Analysis
  85. GRB 250702F: Fermi GBM Observation
  86. GRB 250702F: Leavitt Observatory optical observations
  87. GRB 250702F: AKO Optical Afterglow Detection
  88. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  89. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  90. GRB 250702F: Skynet Optical Observations
  91. GRB 250424A: VIRT Optical Upper Limit
  92. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  93. GRB 250702F: TRT Optical Observation
  94. GRB 250703A: DDOTI Optical Upper Limit
  95. GRB 250702F: REM optical afterglow detection
  96. EP250702a: Global MASTER-Net observations report
  97. GRB 250702F: DDOTI Optical Observation
  98. GRB 250702F: COLIBRÍ Observations of the Afterglow
  99. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  100. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient

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