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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"

43955 results found.

  1. GRB 250226A: Fermi GBM Observation
  2. EP250225a: EP-FXT follow-up observation
  3. EP250223a: J band upper limit by SYSU 80cm telescope
  4. EP250228a: Swift/XRT localisation
  5. EP250228a: Global MASTER-Net observations report
  6. EP250228a: Einstein Probe detection of an X-ray transient
  7. GRB 250226A / EP250226a: LCO detection of the afterglow
  8. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  9. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  10. GRB 250225B: VLT/Xshooter imaging
  11. GRB 250205A / EP250205A: further radio observations with the VLA
  12. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  13. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  14. GRB 250225B: INTEGRAL SPI-ACS detection
  15. EP250225a: NOT optical candidate counterpart
  16. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  17. EP250226a / GRB 250226A: SVOM/VT optical observations
  18. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  19. EP250225a: TRT optical upper limits
  20. EP250226a/GRB 250226A: 1.6m Mephisto observations
  21. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  22. EP250226a/GRB 250226A: Kinder optical follow-up observations
  23. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  24. LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  26. Fermi GRB 250226B: Global MASTER-Net observations report
  27. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  28. GRB 250226B: Fermi GBM Final Real-time Localization
  29. GRB 250225B: Fermi GBM Observation
  30. GRB 250221A: ATCA Detections and Upper Limits
  31. GRB 250225B: REM NIR upper limits
  32. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  33. Konus-Wind detection of GRB 250225B
  34. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  35. EP250223a: CrAO ZTSH optical observation
  36. GRB 250225B: VLT optical and near-infrared candidate counterpart
  37. GRB 250225B: VLT/FORS2 candidate optical afterglow
  38. GRB 250225B: SVOM/GRM observation of a long burst
  39. GRB 250226A: GECAM-B detection
  40. GRB 250221A: EP-FXT detection of the X-ray afterglow
  41. GRB 250214A: SVOM/GRM observation
  42. EP250226a/GRB 250226A: GSP detects optical counterpart
  43. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  44. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  45. EP250226a / GRB 250226A: TRT optical counterpart observation
  46. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  47. EP250226a: Global MASTER-Net observations report
  48. Swift GRB 250225B: Global MASTER-Net observations report
  49. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  50. Fermi GRB 250226A: Global MASTER-Net observations report
  51. Fermi trigger No 762205158: Global MASTER-Net observations report
  52. GRB 250226A: Fermi GBM Final Real-time Localization
  53. EP250225a: Global MASTER-Net observations report
  54. EP250225a: GSP optical upper limit
  55. EP250223a: GMG Optical Observation
  56. EP250225a: Einstein Probe detected of a fast X-ray transient
  57. Fermi GRB 250225A: Global MASTER-Net observations report
  58. GRB 250225B: Swift detection of a burst
  59. EP250223a: GROWTH-India Telescope optical observations
  60. GRB 250221A: Swift-BAT refined analysis
  61. GRB 250223C: SVOM/GRM observation of a long burst
  62. EP250215A: J band upper limit by SYSU 80cm telescope
  63. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  64. GRB 250225A: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  66. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  67. EP250223a: Kinder optical follow-up observations
  68. GRB 250207a: ATCA Radio Upper Limits
  69. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  70. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  71. GRB 250119B: VZLUSAT-2 detection
  72. GRB 250223C: Fermi GBM Final Real-time Localization
  73. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  74. GRB 250202B: VZLUSAT-2 detection
  75. GRB 250219A: EP-FXT afterglow detection
  76. EP250223a: GOTO optical afterglow detections
  77. GRB 250222A: SVOM/GRM observation of a burst
  78. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  79. GRB 250210A: VZLUSAT-2 detection
  80. GRB 250206A: VZLUSAT-2 detection
  81. EP250223a: REM NIR upper limit
  82. EP250223a: TRT optical afterglow observation
  83. EP250223a: refined analysis of the EP-WXT and FXT observations
  84. EP250223a: 1.6m Mephisto and 50cm array observations
  85. GRB 250221A: TNOT detection of the optical counterpart
  86. EP250223a: SVOM/VT optical observation
  87. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  88. 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
  89. The EP-WXT trigger 01709131882 is likely a flaring star
  90. EP250223a: OASDG optical observations
  91. EP250223a: LCO detection of the afterglow
  92. EP250223a: early optical detection by BOOTES-4
  93. EP250223a: NOT redshift z = 2.756
  94. EP250223a: Swift/XRT localization
  95. EP250223a: NOT optical afterglow candidate
  96. GRB 250223B: Fermi GBM Final Localization
  97. EP250223a: Global MASTER-Net observations report
  98. GRB 250221A: VLA radio detection
  99. Fermi GRB 250223A: Global MASTER-Net observations report
  100. Fermi trigger No 762020305: Global MASTER-Net observations report

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