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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"

32762 results found.

  1. EP250302A: VLT near-infrared observations
  2. EP250302A: VLT/X-shooter tentative redshift
  3. EP250302a: OHP/T193 optical and spectroscopic observations
  4. EP250302a: Global MASTER-Net observations report
  5. EP250302a: Xinglong F60B optical observation
  6. EP250302a: Swift-XRT observations of a fading X-ray source
  7. EP250302a: Einstein Probe detection of an X-ray transient
  8. EP250302a: SVOM/C-GFT optical observations
  9. GRB 250226A: GRANDMA Optical Observations
  10. EP250302a: Montarrenti Observatory optical detection
  11. Fermi GRB 250302A: Global MASTER-Net observations report
  12. EP250302a: FTW optical and NIR detection
  13. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  14. GRB 250225B: VLT near-infrared afterglow confirmation
  15. EP250228a: Optical observations with Kinder and Swift/UVOT
  16. Konus-Wind detection of GRB 250226A
  17. GRB 250225B: EIRSAT-1 GMOD Detection
  18. GRB 250226A: KAO Optical Upper Limit
  19. GRB 250226A: AbAO AS-32 Optical Upper Limit
  20. EP250227a: Global MASTER-Net observations report
  21. EP250223A: Upper limits from Fermi-GBM Observations
  22. EP250227a: TRT optical upper limit
  23. GRB 250225B: VLT/HAWKI near-infrared observations
  24. EP250227a: Optical upper limits with Kinder observations
  25. EP250227a: NOT optical observations
  26. EP250228a: updates on the EP observations
  27. GRB 250226A: Fermi GBM Observation
  28. EP250225a: EP-FXT follow-up observation
  29. EP250223a: J band upper limit by SYSU 80cm telescope
  30. EP250228a: Swift/XRT localisation
  31. EP250228a: Global MASTER-Net observations report
  32. GRB 250226A / EP250226a: LCO detection of the afterglow
  33. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  34. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  35. GRB 250225B: VLT/Xshooter imaging
  36. GRB 250205A / EP250205A: further radio observations with the VLA
  37. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  38. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  39. GRB 250225B: INTEGRAL SPI-ACS detection
  40. EP250225a: NOT optical candidate counterpart
  41. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  42. EP250226a / GRB 250226A: SVOM/VT optical observations
  43. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  44. EP250225a: TRT optical upper limits
  45. EP250226a/GRB 250226A: 1.6m Mephisto observations
  46. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  47. EP250226a/GRB 250226A: Kinder optical follow-up observations
  48. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  49. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  50. Fermi GRB 250226B: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  52. GRB 250225B: Fermi GBM Observation
  53. GRB 250221A: ATCA Detections and Upper Limits
  54. GRB 250225B: REM NIR upper limits
  55. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  56. Konus-Wind detection of GRB 250225B
  57. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  58. EP250223a: CrAO ZTSH optical observation
  59. GRB 250225B: VLT optical and near-infrared candidate counterpart
  60. GRB 250225B: VLT/FORS2 candidate optical afterglow
  61. GRB 250225B: SVOM/GRM observation of a long burst
  62. GRB 250226A: GECAM-B detection
  63. GRB 250221A: EP-FXT detection of the X-ray afterglow
  64. GRB 250214A: SVOM/GRM observation
  65. EP250226a/GRB 250226A: GSP detects optical counterpart
  66. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  67. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  68. EP250226a / GRB 250226A: TRT optical counterpart observation
  69. EP250226a: Global MASTER-Net observations report
  70. Swift GRB 250225B: Global MASTER-Net observations report
  71. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  72. Fermi GRB 250226A: Global MASTER-Net observations report
  73. EP250225a: Global MASTER-Net observations report
  74. EP250225a: GSP optical upper limit
  75. EP250223a: GMG Optical Observation
  76. Fermi GRB 250225A: Global MASTER-Net observations report
  77. EP250223a: GROWTH-India Telescope optical observations
  78. GRB 250221A: Swift-BAT refined analysis
  79. GRB 250223C: SVOM/GRM observation of a long burst
  80. EP250215A: J band upper limit by SYSU 80cm telescope
  81. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  82. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  83. EP250223a: Kinder optical follow-up observations
  84. GRB 250207a: ATCA Radio Upper Limits
  85. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  86. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  87. GRB 250119B: VZLUSAT-2 detection
  88. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  89. GRB 250202B: VZLUSAT-2 detection
  90. GRB 250219A: EP-FXT afterglow detection
  91. EP250223a: GOTO optical afterglow detections
  92. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  93. GRB 250210A: VZLUSAT-2 detection
  94. GRB 250206A: VZLUSAT-2 detection
  95. EP250223a: REM NIR upper limit
  96. EP250223a: TRT optical afterglow observation
  97. EP250223a: refined analysis of the EP-WXT and FXT observations
  98. EP250223a: 1.6m Mephisto and 50cm array observations
  99. GRB 250221A: TNOT detection of the optical counterpart
  100. EP250223a: SVOM/VT optical observation

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