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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"

45685 results found.

  1. EP250225a: NOT optical candidate counterpart
  2. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  3. EP250226a / GRB 250226A: SVOM/VT optical observations
  4. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  5. EP250225a: TRT optical upper limits
  6. EP250226a/GRB 250226A: 1.6m Mephisto observations
  7. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  8. EP250226a/GRB 250226A: Kinder optical follow-up observations
  9. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  10. LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  12. Fermi GRB 250226B: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  14. GRB 250226B: Fermi GBM Final Real-time Localization
  15. GRB 250225B: Fermi GBM Observation
  16. GRB 250221A: ATCA Detections and Upper Limits
  17. GRB 250225B: REM NIR upper limits
  18. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  19. Konus-Wind detection of GRB 250225B
  20. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  21. EP250223a: CrAO ZTSH optical observation
  22. GRB 250225B: VLT optical and near-infrared candidate counterpart
  23. GRB 250225B: VLT/FORS2 candidate optical afterglow
  24. GRB 250225B: SVOM/GRM observation of a long burst
  25. GRB 250226A: GECAM-B detection
  26. GRB 250221A: EP-FXT detection of the X-ray afterglow
  27. GRB 250214A: SVOM/GRM observation
  28. EP250226a/GRB 250226A: GSP detects optical counterpart
  29. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  30. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  31. EP250226a / GRB 250226A: TRT optical counterpart observation
  32. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  33. EP250226a: Global MASTER-Net observations report
  34. Swift GRB 250225B: Global MASTER-Net observations report
  35. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  36. Fermi GRB 250226A: Global MASTER-Net observations report
  37. Fermi trigger No 762205158: Global MASTER-Net observations report
  38. GRB 250226A: Fermi GBM Final Real-time Localization
  39. EP250225a: Global MASTER-Net observations report
  40. EP250225a: GSP optical upper limit
  41. EP250223a: GMG Optical Observation
  42. EP250225a: Einstein Probe detected of a fast X-ray transient
  43. Fermi GRB 250225A: Global MASTER-Net observations report
  44. GRB 250225B: Swift detection of a burst
  45. EP250223a: GROWTH-India Telescope optical observations
  46. GRB 250221A: Swift-BAT refined analysis
  47. GRB 250223C: SVOM/GRM observation of a long burst
  48. EP250215A: J band upper limit by SYSU 80cm telescope
  49. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  50. GRB 250225A: Fermi GBM Final Real-time Localization
  51. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  52. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  53. EP250223a: Kinder optical follow-up observations
  54. GRB 250207a: ATCA Radio Upper Limits
  55. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  56. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  57. GRB 250119B: VZLUSAT-2 detection
  58. GRB 250223C: Fermi GBM Final Real-time Localization
  59. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  60. GRB 250202B: VZLUSAT-2 detection
  61. GRB 250219A: EP-FXT afterglow detection
  62. EP250223a: GOTO optical afterglow detections
  63. GRB 250222A: SVOM/GRM observation of a burst
  64. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  65. GRB 250210A: VZLUSAT-2 detection
  66. GRB 250206A: VZLUSAT-2 detection
  67. EP250223a: REM NIR upper limit
  68. EP250223a: TRT optical afterglow observation
  69. EP250223a: refined analysis of the EP-WXT and FXT observations
  70. EP250223a: 1.6m Mephisto and 50cm array observations
  71. GRB 250221A: TNOT detection of the optical counterpart
  72. EP250223a: SVOM/VT optical observation
  73. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  74. 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
  75. The EP-WXT trigger 01709131882 is likely a flaring star
  76. EP250223a: OASDG optical observations
  77. EP250223a: LCO detection of the afterglow
  78. EP250223a: early optical detection by BOOTES-4
  79. EP250223a: NOT redshift z = 2.756
  80. EP250223a: Swift/XRT localization
  81. EP250223a: NOT optical afterglow candidate
  82. GRB 250223B: Fermi GBM Final Localization
  83. EP250223a: Global MASTER-Net observations report
  84. GRB 250221A: VLA radio detection
  85. Fermi GRB 250223A: Global MASTER-Net observations report
  86. Fermi trigger No 762020305: Global MASTER-Net observations report
  87. GRB 250223A: Fermi GBM Final Real-time Localization
  88. EP250223a: Einstein Probe detection of an X-ray transient
  89. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  90. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  91. GRB 250221A: continued Mondy optical observations, brightening afterglow
  92. GRB 250221A: Optical counterpart detection by LCO.
  93. GRB 250221A: Mondy optical observations
  94. Konus-Wind detection of GRB 250221A
  95. GRB 250221A: Assy optical observations
  96. EP250220a: FTW optical and NIR observations and upper limits
  97. EP250220a: EP-FXT follow-up observations
  98. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  99. GRB 250221A: VLT/X-shooter redshift z = 0.768
  100. GRB 250221A: GRANDMA/TAROT Detection

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