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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. GRB 250205A / EP250205A: further radio observations with the VLA
  2. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  3. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  4. GRB 250225B: INTEGRAL SPI-ACS detection
  5. EP250225a: NOT optical candidate counterpart
  6. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  7. EP250226a / GRB 250226A: SVOM/VT optical observations
  8. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  9. EP250225a: TRT optical upper limits
  10. EP250226a/GRB 250226A: 1.6m Mephisto observations
  11. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  12. EP250226a/GRB 250226A: Kinder optical follow-up observations
  13. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  14. LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  16. Fermi GRB 250226B: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  18. GRB 250226B: Fermi GBM Final Real-time Localization
  19. GRB 250225B: Fermi GBM Observation
  20. GRB 250221A: ATCA Detections and Upper Limits
  21. GRB 250225B: REM NIR upper limits
  22. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  23. Konus-Wind detection of GRB 250225B
  24. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  25. EP250223a: CrAO ZTSH optical observation
  26. GRB 250225B: VLT optical and near-infrared candidate counterpart
  27. GRB 250225B: VLT/FORS2 candidate optical afterglow
  28. GRB 250225B: SVOM/GRM observation of a long burst
  29. GRB 250226A: GECAM-B detection
  30. GRB 250221A: EP-FXT detection of the X-ray afterglow
  31. GRB 250214A: SVOM/GRM observation
  32. EP250226a/GRB 250226A: GSP detects optical counterpart
  33. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  34. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  35. EP250226a / GRB 250226A: TRT optical counterpart observation
  36. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  37. EP250226a: Global MASTER-Net observations report
  38. Swift GRB 250225B: Global MASTER-Net observations report
  39. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  40. Fermi GRB 250226A: Global MASTER-Net observations report
  41. Fermi trigger No 762205158: Global MASTER-Net observations report
  42. GRB 250226A: Fermi GBM Final Real-time Localization
  43. EP250225a: Global MASTER-Net observations report
  44. EP250225a: GSP optical upper limit
  45. EP250223a: GMG Optical Observation
  46. EP250225a: Einstein Probe detected of a fast X-ray transient
  47. Fermi GRB 250225A: Global MASTER-Net observations report
  48. GRB 250225B: Swift detection of a burst
  49. EP250223a: GROWTH-India Telescope optical observations
  50. GRB 250221A: Swift-BAT refined analysis
  51. GRB 250223C: SVOM/GRM observation of a long burst
  52. EP250215A: J band upper limit by SYSU 80cm telescope
  53. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  54. GRB 250225A: Fermi GBM Final Real-time Localization
  55. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  56. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  57. EP250223a: Kinder optical follow-up observations
  58. GRB 250207a: ATCA Radio Upper Limits
  59. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  60. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  61. GRB 250119B: VZLUSAT-2 detection
  62. GRB 250223C: Fermi GBM Final Real-time Localization
  63. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  64. GRB 250202B: VZLUSAT-2 detection
  65. GRB 250219A: EP-FXT afterglow detection
  66. EP250223a: GOTO optical afterglow detections
  67. GRB 250222A: SVOM/GRM observation of a burst
  68. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  69. GRB 250210A: VZLUSAT-2 detection
  70. GRB 250206A: VZLUSAT-2 detection
  71. EP250223a: REM NIR upper limit
  72. EP250223a: TRT optical afterglow observation
  73. EP250223a: refined analysis of the EP-WXT and FXT observations
  74. EP250223a: 1.6m Mephisto and 50cm array observations
  75. GRB 250221A: TNOT detection of the optical counterpart
  76. EP250223a: SVOM/VT optical observation
  77. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  78. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  79. The EP-WXT trigger 01709131882 is likely a flaring star
  80. EP250223a: OASDG optical observations
  81. EP250223a: LCO detection of the afterglow
  82. EP250223a: early optical detection by BOOTES-4
  83. EP250223a: NOT redshift z = 2.756
  84. EP250223a: Swift/XRT localization
  85. EP250223a: NOT optical afterglow candidate
  86. GRB 250223B: Fermi GBM Final Localization
  87. EP250223a: Global MASTER-Net observations report
  88. GRB 250221A: VLA radio detection
  89. Fermi GRB 250223A: Global MASTER-Net observations report
  90. Fermi trigger No 762020305: Global MASTER-Net observations report
  91. GRB 250223A: Fermi GBM Final Real-time Localization
  92. EP250223a: Einstein Probe detection of an X-ray transient
  93. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  94. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  95. GRB 250221A: continued Mondy optical observations, brightening afterglow
  96. GRB 250221A: Optical counterpart detection by LCO.
  97. GRB 250221A: Mondy optical observations
  98. Konus-Wind detection of GRB 250221A
  99. GRB 250221A: Assy optical observations
  100. EP250220a: FTW optical and NIR observations and upper limits

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