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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"

20491 results found.

  1. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  2. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  3. GRB 250702B,D,E / EP250702a: ALMA detection
  4. IceCube-250708A: No Candidates from WINTER
  5. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  6. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  7. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  8. EP/WXT 01709181970: GOTO observations confirm stellar variability
  9. EP250704a/GRB 250704B: 10 GHz VLA detection
  10. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  11. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  12. IceCube-250706A: No Candidates from WINTER
  13. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  14. GRB 250704B / EP250704a: VLA radio detection
  15. Fermi GRB 250708A: Global MASTER-Net observations report
  16. IceCube-250708A: Global MASTER-Net observations report
  17. EP250704a/GRB250704B : HCT optical and NIR upper limits
  18. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  19. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  20. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  21. GRB 250702F: radio detection with the VLA
  22. IceCube-250706A: EP-FXT follow-up observations
  23. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  24. IceCube-250706A: Global MASTER-Net observations report
  25. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  26. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  27. GRB 250706B: Swift/UVOT Detection
  28. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  29. GRB 250702F: GRANDMA observations
  30. GRB 250706B: refined SVOM/MXT data analysis
  31. GRB 250706A: Swift/UVOT Upper Limits
  32. GRB 250706B: REM optical observations
  33. GRB 250706A: REM optical/NIR observations
  34. IceCube-250416A: DDOTI Optical Upper Limit
  35. IceCube-250706A: COLIBRÍ optical upper limits
  36. Swift GRB 250706A: Global MASTER-Net observations report
  37. GRB 250706A: JinShan optical upper limits
  38. GRB 250706A: SAO RAS optical observations
  39. EP250704A: NOWT Detection
  40. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  41. GRB250706B: Swift-XRT counterpart detection
  42. GRB 250706B: iTelescope optical observations
  43. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  44. GRB 250706B: TRT bright optical counterpart detection
  45. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  46. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  47. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  48. GRB 250704B: Swift/UVOT Upper Limits
  49. GRB 250704A: Swift/UVOT Detection
  50. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  51. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  52. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  53. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  54. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  55. GRB 250702F: Kilonova-Catcher optical afterglow detection
  56. GRB 250702F: Monte Agliale Observatory optical observations
  57. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  58. EP250704a / GRB 250704B: JinShan optical observations
  59. EP250704a / GRB 250704B: SAO RAS optical observations
  60. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  61. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  62. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  63. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  64. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  65. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  66. EP250704a / GRB250704B: Swift-XRT counterpart detection
  67. GRB 250702B / EP2050702a: FTW optical and NIR observations
  68. EP250704a / GRB 250704B - REM observations
  69. GRB 250702F: GROWTH-India Telescope optical observations
  70. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  71. EP250702a: WFST optical observations
  72. EP250704a: COLIBRÍ optical counterpart candidate
  73. GRB 250702F: optical photometry from Konkoly
  74. GRB 250704A: REM detection of the optical afterglow
  75. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  76. GRB 250702F: Swift/UVOT Detection
  77. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  78. Fermi GRB 250703A: Global MASTER-Net observations report
  79. GRB 250702F: Leavitt Observatory optical observations
  80. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  81. GRB 250702F: Skynet Optical Observations
  82. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  83. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  84. GRB 250702F: TRT Optical Observation
  85. GRB 250703A: DDOTI Optical Upper Limit
  86. GRB 250702F: REM optical afterglow detection
  87. EP250702a: Global MASTER-Net observations report
  88. GRB 250702F: DDOTI Optical Observation
  89. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  90. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  91. GRB 250702F: COLIBRÍ Observations of the Afterglow
  92. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  93. Fermi GRB 250702E: Global MASTER-Net observations report
  94. Fermi GRB 250702B: Global MASTER-Net observations report
  95. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  96. GRB 250702F: NOT observations of the optical afterglow
  97. GRB 250702F: MASTER optical afterglow observation
  98. Fermi GRB 250702F: Global MASTER-Net observations report
  99. Fermi GRB 250702C: Global MASTER-Net observations report
  100. GRB 250702F: GOTO optical counterpart detection

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