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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. EP250302a: SVOM/VT optical observation
  2. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  3. EP250302a: SAO RAS optical observations
  4. EP250302a : GIT optical follow-up
  5. EP250302a: VLT/X-shooter redshift confirmation
  6. EP250225a: the candidate optical counterpart is an AGN
  7. EP250302a: Kinder optical follow-up observations
  8. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  9. EP250302a: Swift/UVOT detection
  10. EP250302a: NUTTelA-TAO Early Measurments
  11. EP250302a: optical observation from the INAF Asiago Observatory
  12. EP250302a: REM NIR upper limits
  13. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  14. EP250302a: Mondy Observations and Optical Light Curve
  15. EP250302a: VLT/MUSE optical redshift z = 1.131
  16. INTEGRAL: end of scientific operations
  17. EP250302A: VLT near-infrared observations
  18. EP250302A: VLT/X-shooter tentative redshift
  19. EP250302a: OHP/T193 optical and spectroscopic observations
  20. EP250302a: Global MASTER-Net observations report
  21. EP250302a: Xinglong F60B optical observation
  22. EP250302a: Swift-XRT observations of a fading X-ray source
  23. EP250302a: Einstein Probe detection of an X-ray transient
  24. EP250302a: SVOM/C-GFT optical observations
  25. GRB 250226A: GRANDMA Optical Observations
  26. EP250302a: Montarrenti Observatory optical detection
  27. Fermi GRB 250302A: Global MASTER-Net observations report
  28. EP250302a: FTW optical and NIR detection
  29. EP250302a: Nanshan/HMT optical counterpart detection
  30. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  31. GRB 250302A: Fermi GBM Final Real-time Localization
  32. GRB 250228A: Fermi GBM Final Localization
  33. The EP-WXT trigger 01709132140 is likely a flaring star
  34. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  35. GRB 250225B: VLT near-infrared afterglow confirmation
  36. EP250228a: Optical observations with Kinder and Swift/UVOT
  37. Konus-Wind detection of GRB 250226A
  38. GRB 250225B: EIRSAT-1 GMOD Detection
  39. GRB 250226A: KAO Optical Upper Limit
  40. GRB 250226A: AbAO AS-32 Optical Upper Limit
  41. EP250227a: Global MASTER-Net observations report
  42. EP250223A: Upper limits from Fermi-GBM Observations
  43. EP250227a: TRT optical upper limit
  44. GRB 250225B: VLT/HAWKI near-infrared observations
  45. EP250227a: Optical upper limits with Kinder observations
  46. EP250227a: NOT optical observations
  47. EP250227a: Einstein Probe detected of a fast X-ray transient
  48. EP250228a: updates on the EP observations
  49. GRB 250226A: Fermi GBM Observation
  50. EP250225a: EP-FXT follow-up observation
  51. EP250223a: J band upper limit by SYSU 80cm telescope
  52. EP250228a: Swift/XRT localisation
  53. EP250228a: Global MASTER-Net observations report
  54. EP250228a: Einstein Probe detection of an X-ray transient
  55. GRB 250226A / EP250226a: LCO detection of the afterglow
  56. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  57. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  58. GRB 250225B: VLT/Xshooter imaging
  59. GRB 250205A / EP250205A: further radio observations with the VLA
  60. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  61. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  62. GRB 250225B: INTEGRAL SPI-ACS detection
  63. EP250225a: NOT optical candidate counterpart
  64. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  65. EP250226a / GRB 250226A: SVOM/VT optical observations
  66. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  67. EP250225a: TRT optical upper limits
  68. EP250226a/GRB 250226A: 1.6m Mephisto observations
  69. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  70. EP250226a/GRB 250226A: Kinder optical follow-up observations
  71. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  72. LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  74. Fermi GRB 250226B: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  76. GRB 250226B: Fermi GBM Final Real-time Localization
  77. GRB 250225B: Fermi GBM Observation
  78. GRB 250221A: ATCA Detections and Upper Limits
  79. GRB 250225B: REM NIR upper limits
  80. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  81. Konus-Wind detection of GRB 250225B
  82. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  83. EP250223a: CrAO ZTSH optical observation
  84. GRB 250225B: VLT optical and near-infrared candidate counterpart
  85. GRB 250225B: VLT/FORS2 candidate optical afterglow
  86. GRB 250225B: SVOM/GRM observation of a long burst
  87. GRB 250226A: GECAM-B detection
  88. GRB 250221A: EP-FXT detection of the X-ray afterglow
  89. GRB 250214A: SVOM/GRM observation
  90. EP250226a/GRB 250226A: GSP detects optical counterpart
  91. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  92. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  93. EP250226a / GRB 250226A: TRT optical counterpart observation
  94. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  95. EP250226a: Global MASTER-Net observations report
  96. Swift GRB 250225B: Global MASTER-Net observations report
  97. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  98. Fermi GRB 250226A: Global MASTER-Net observations report
  99. Fermi trigger No 762205158: Global MASTER-Net observations report
  100. GRB 250226A: Fermi GBM Final Real-time Localization

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