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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"

21953 results found.

  1. EP250308a: GSP optical upper limit
  2. EP250308a: FTW optical and NIR upper limits
  3. EP250308a: Einstein Probe detection of an X-ray transient
  4. Fermi GRB 250307A: Global MASTER-Net observations report
  5. EP250304a: MeerKAT detection of a possible radio counterpart
  6. EP250302a:Xinglong optical observations
  7. Fermi trigger No 762963055: Global MASTER-Net observations report
  8. Swift GRB 250306A: Global MASTER-Net observations report
  9. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  10. GRB250101A: Radio upper limits from VLA observations
  11. EP250304A: Upper limits from Fermi-GBM Observations
  12. Fermi GRB 250305A: Global MASTER-Net observations report
  13. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  14. EP250302a: Optical Observations at CrAO and SAO RAS
  15. EP 250304A: Optical counterpart detection by LCO
  16. EP250302A: 1.3m DFOT optical afterglow detection
  17. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  18. EP250304a: REM NIR upper limits
  19. EP250302a: Mondy Continued Optical Observations
  20. EP250304a: TRT optical counterpart detection
  21. EP250304a: Global MASTER-Net observations report
  22. EP250302a: SVOM/VT optical observation
  23. EP250302a: SAO RAS optical observations
  24. EP250225a: the candidate optical counterpart is an AGN
  25. EP250302a: Kinder optical follow-up observations
  26. EP250302a: NUTTelA-TAO Early Measurments
  27. EP250302a: REM NIR upper limits
  28. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  29. EP250302a: Mondy Observations and Optical Light Curve
  30. EP250302a: VLT/MUSE optical redshift z = 1.131
  31. EP250302A: VLT near-infrared observations
  32. EP250302A: VLT/X-shooter tentative redshift
  33. EP250302a: OHP/T193 optical and spectroscopic observations
  34. EP250302a: Global MASTER-Net observations report
  35. EP250302a: Xinglong F60B optical observation
  36. EP250302a: Swift-XRT observations of a fading X-ray source
  37. EP250302a: Einstein Probe detection of an X-ray transient
  38. EP250302a: SVOM/C-GFT optical observations
  39. GRB 250226A: GRANDMA Optical Observations
  40. EP250302a: Montarrenti Observatory optical detection
  41. Fermi GRB 250302A: Global MASTER-Net observations report
  42. EP250302a: FTW optical and NIR detection
  43. EP250302a: Nanshan/HMT optical counterpart detection
  44. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  45. GRB 250225B: VLT near-infrared afterglow confirmation
  46. EP250228a: Optical observations with Kinder and Swift/UVOT
  47. GRB 250226A: KAO Optical Upper Limit
  48. GRB 250226A: AbAO AS-32 Optical Upper Limit
  49. EP250227a: Global MASTER-Net observations report
  50. EP250223A: Upper limits from Fermi-GBM Observations
  51. EP250227a: TRT optical upper limit
  52. GRB 250225B: VLT/HAWKI near-infrared observations
  53. EP250227a: Optical upper limits with Kinder observations
  54. EP250227a: NOT optical observations
  55. EP250228a: updates on the EP observations
  56. EP250223a: J band upper limit by SYSU 80cm telescope
  57. EP250228a: Global MASTER-Net observations report
  58. GRB 250226A / EP250226a: LCO detection of the afterglow
  59. GRB 250225B: VLT/Xshooter imaging
  60. GRB 250205A / EP250205A: further radio observations with the VLA
  61. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  62. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  63. GRB 250225B: INTEGRAL SPI-ACS detection
  64. EP250225a: NOT optical candidate counterpart
  65. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  66. EP250226a / GRB 250226A: SVOM/VT optical observations
  67. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  68. EP250225a: TRT optical upper limits
  69. EP250226a/GRB 250226A: 1.6m Mephisto observations
  70. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  71. EP250226a/GRB 250226A: Kinder optical follow-up observations
  72. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  73. Fermi GRB 250226B: Global MASTER-Net observations report
  74. GRB 250221A: ATCA Detections and Upper Limits
  75. GRB 250225B: REM NIR upper limits
  76. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  77. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  78. GRB 250225B: VLT optical and near-infrared candidate counterpart
  79. GRB 250225B: VLT/FORS2 candidate optical afterglow
  80. GRB 250221A: EP-FXT detection of the X-ray afterglow
  81. EP250226a/GRB 250226A: GSP detects optical counterpart
  82. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  83. EP250226a: Global MASTER-Net observations report
  84. Swift GRB 250225B: Global MASTER-Net observations report
  85. Fermi GRB 250226A: Global MASTER-Net observations report
  86. Fermi trigger No 762205158: Global MASTER-Net observations report
  87. EP250225a: Global MASTER-Net observations report
  88. EP250225a: GSP optical upper limit
  89. EP250225a: Einstein Probe detected of a fast X-ray transient
  90. Fermi GRB 250225A: Global MASTER-Net observations report
  91. GRB 250225B: Swift detection of a burst
  92. EP250223a: GROWTH-India Telescope optical observations
  93. EP250215A: J band upper limit by SYSU 80cm telescope
  94. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  95. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  96. EP250223a: Kinder optical follow-up observations
  97. GRB 250207a: ATCA Radio Upper Limits
  98. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  99. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  100. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert

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