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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"
  1. EP250711a: COLIBRÍ continuous optical observations
  2. GRB 250706A: Swift-BAT refined analysis
  3. GRB 250702F: Swift-BAT refined analysis
  4. GRB 250628A: Swift-BAT refined analysis
  5. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  6. GRB 250713A: JinShan optical upper limits
  7. GRB 250713A: SVOM detection of a long burst
  8. EP250711a: Global MASTER-Net observations report
  9. GRB 250711A: DDOTI Optical Upper Limit
  10. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  11. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  12. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  13. GRB 250711A: SVOM/GRM observation
  14. EP250711a: NOT optical counterpart candidate
  15. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  16. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  17. Fermi GRB 250711A: Global MASTER-Net observations report
  18. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  19. GRB 250704A: GRANDMA observations
  20. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  21. GRB 250711A: Fermi GBM Final Real-time Localization
  22. GRB 250704A: SVOM/ECLAIRs refined analysis
  23. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  24. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  25. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  26. GRB 250702B,D,E / EP250702a: ALMA detection
  27. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  28. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  29. IceCube-250708A: No Candidates from WINTER
  30. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  31. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  32. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  33. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 250709A: Fermi GBM Final Localization
  35. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  36. GRB 250706B/C: Insight-HXMT detection
  37. EP/WXT 01709181970: GOTO observations confirm stellar variability
  38. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  39. EP250704a/GRB 250704B: 10 GHz VLA detection
  40. The EP-WXT trigger 01709181970 is likely a flaring star
  41. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  42. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  43. IceCube-250706A: No Candidates from WINTER
  44. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  45. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  46. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 250704B / EP250704a: VLA radio detection
  48. Fermi GRB 250708A: Global MASTER-Net observations report
  49. IceCube-250708A: Global MASTER-Net observations report
  50. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  51. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  52. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  53. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  54. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  55. EP250704a/GRB250704B : HCT optical and NIR upper limits
  56. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  57. GRB 250708A: Fermi GBM Final Real-time Localization
  58. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  59. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  60. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  61. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  62. GRB 250702F: radio detection with the VLA
  63. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  64. IceCube-250706A: EP-FXT follow-up observations
  65. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  66. GRB 250706B/C: Fermi-LAT detection
  67. IceCube-250706A: Global MASTER-Net observations report
  68. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  69. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  70. GRB 250706B: Swift/UVOT Detection
  71. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  72. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  73. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  74. GRB 250702F: GRANDMA observations
  75. GRB 250706A: Swift-XRT refined Analysis
  76. GRB 250706B: refined SVOM/MXT data analysis
  77. GRB 250706A: Swift/UVOT Upper Limits
  78. GRB 250706B: REM optical observations
  79. GRB 250706A: REM optical/NIR observations
  80. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  81. IceCube-250416A: DDOTI Optical Upper Limit
  82. IceCube-250706A: COLIBRÍ optical upper limits
  83. Swift GRB 250706A: Global MASTER-Net observations report
  84. GRB 250706A: JinShan optical upper limits
  85. GRB 250706A: SAO RAS optical observations
  86. EP250704A: NOWT Detection
  87. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  88. The EP-WXT trigger 01709181580 is likely a flaring star
  89. GRB250706B: Swift-XRT counterpart detection
  90. GRB 250706B: iTelescope optical observations
  91. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  92. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  93. GRB 250706B: SVOM/VT optical observation
  94. GRB 250706B: TRT bright optical counterpart detection
  95. GRB 250706A: GROWTH-India Telescope optical upper limit
  96. GRB 250706B: SVOM detection of a long burst
  97. GRB 250706A: Swift detection of a burst
  98. GRB 250704B: Swift-XRT refined Analysis
  99. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  100. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart

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