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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"

32494 results found.

  1. GRB 250713A: SVOM/VT optical upper limit
  2. GRB 250713A: NOT optical upper limits
  3. GRB 250713A: OHP/T193 upper limit
  4. GRB 250713A: SVOM/C-GFT upper limit
  5. GRB 250706B/C: 7DT Follow-up Observations
  6. GRB 250713A: EP-FXT counterpart detection
  7. EP250711a: COLIBRÍ continuous optical observations
  8. GRB 250706A: Swift-BAT refined analysis
  9. GRB 250702F: Swift-BAT refined analysis
  10. GRB 250628A: Swift-BAT refined analysis
  11. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  12. GRB 250713A: JinShan optical upper limits
  13. EP250711a: Global MASTER-Net observations report
  14. GRB 250711A: DDOTI Optical Upper Limit
  15. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  16. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  17. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  18. GRB 250711A: SVOM/GRM observation
  19. EP250711a: NOT optical counterpart candidate
  20. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  21. Fermi GRB 250711A: Global MASTER-Net observations report
  22. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  23. GRB 250704A: GRANDMA observations
  24. GRB 250704A: SVOM/ECLAIRs refined analysis
  25. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  26. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  27. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  28. GRB 250702B,D,E / EP250702a: ALMA detection
  29. IceCube-250708A: No Candidates from WINTER
  30. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  31. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  32. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  33. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  34. GRB 250706B/C: Insight-HXMT detection
  35. EP/WXT 01709181970: GOTO observations confirm stellar variability
  36. EP250704a/GRB 250704B: 10 GHz VLA detection
  37. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  38. IceCube-250706A: No Candidates from WINTER
  39. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  40. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  41. GRB 250704B / EP250704a: VLA radio detection
  42. Fermi GRB 250708A: Global MASTER-Net observations report
  43. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  44. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  45. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  46. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  47. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  48. EP250704a/GRB250704B : HCT optical and NIR upper limits
  49. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  50. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  51. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  52. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  53. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  54. GRB 250702F: radio detection with the VLA
  55. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  56. IceCube-250706A: EP-FXT follow-up observations
  57. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  58. GRB 250706B/C: Fermi-LAT detection
  59. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  60. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  61. GRB 250706B: Swift/UVOT Detection
  62. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  63. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  64. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  65. GRB 250702F: GRANDMA observations
  66. GRB 250706B: refined SVOM/MXT data analysis
  67. GRB 250706A: Swift/UVOT Upper Limits
  68. GRB 250706B: REM optical observations
  69. GRB 250706A: REM optical/NIR observations
  70. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  71. IceCube-250416A: DDOTI Optical Upper Limit
  72. IceCube-250706A: COLIBRÍ optical upper limits
  73. Swift GRB 250706A: Global MASTER-Net observations report
  74. GRB 250706A: JinShan optical upper limits
  75. GRB 250706A: SAO RAS optical observations
  76. EP250704A: NOWT Detection
  77. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  78. GRB250706B: Swift-XRT counterpart detection
  79. GRB 250706B: iTelescope optical observations
  80. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  81. GRB 250706B: SVOM/VT optical observation
  82. GRB 250706B: TRT bright optical counterpart detection
  83. GRB 250706A: GROWTH-India Telescope optical upper limit
  84. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  85. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  86. GRB 250703A: EIRSAT-1 GMOD Detection
  87. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  88. GRB 250704B: Swift/UVOT Upper Limits
  89. GRB 250704A: Swift/UVOT Detection
  90. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  91. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  92. GRB 250704B: Insight-HXMT detection
  93. Konus-Wind detection of GRB 250703A
  94. IPN triangulation of GRB 250703A
  95. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  96. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  97. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  98. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  99. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  100. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection

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