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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"

28287 results found.

  1. EP250302A: VLT/X-shooter tentative redshift
  2. EP250302a: OHP/T193 optical and spectroscopic observations
  3. EP250302a: Swift-XRT observations of a fading X-ray source
  4. EP250302a: Einstein Probe detection of an X-ray transient
  5. EP250302a: SVOM/C-GFT optical observations
  6. GRB 250226A: GRANDMA Optical Observations
  7. EP250302a: Montarrenti Observatory optical detection
  8. EP250302a: Nanshan/HMT optical counterpart detection
  9. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  10. GRB 250225B: VLT near-infrared afterglow confirmation
  11. EP250228a: Optical observations with Kinder and Swift/UVOT
  12. Konus-Wind detection of GRB 250226A
  13. GRB 250225B: EIRSAT-1 GMOD Detection
  14. GRB 250226A: KAO Optical Upper Limit
  15. GRB 250226A: AbAO AS-32 Optical Upper Limit
  16. EP250227a: Global MASTER-Net observations report
  17. EP250223A: Upper limits from Fermi-GBM Observations
  18. EP250227a: TRT optical upper limit
  19. GRB 250225B: VLT/HAWKI near-infrared observations
  20. EP250227a: Optical upper limits with Kinder observations
  21. EP250227a: NOT optical observations
  22. EP250227a: Einstein Probe detected of a fast X-ray transient
  23. EP250228a: updates on the EP observations
  24. GRB 250226A: Fermi GBM Observation
  25. EP250223a: J band upper limit by SYSU 80cm telescope
  26. EP250228a: Swift/XRT localisation
  27. EP250228a: Einstein Probe detection of an X-ray transient
  28. GRB 250226A / EP250226a: LCO detection of the afterglow
  29. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  30. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  31. GRB 250225B: VLT/Xshooter imaging
  32. GRB 250205A / EP250205A: further radio observations with the VLA
  33. EP250225a: NOT optical candidate counterpart
  34. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  35. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  36. EP250225a: TRT optical upper limits
  37. EP250226a/GRB 250226A: 1.6m Mephisto observations
  38. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  39. EP250226a/GRB 250226A: Kinder optical follow-up observations
  40. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  41. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  43. GRB 250225B: Fermi GBM Observation
  44. GRB 250225B: REM NIR upper limits
  45. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  46. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  47. EP250223a: CrAO ZTSH optical observation
  48. GRB 250225B: VLT optical and near-infrared candidate counterpart
  49. GRB 250225B: SVOM/GRM observation of a long burst
  50. EP250226a/GRB 250226A: GSP detects optical counterpart
  51. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  52. EP250226a / GRB 250226A: TRT optical counterpart observation
  53. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  54. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  55. EP250225a: GSP optical upper limit
  56. EP250223a: GMG Optical Observation
  57. EP250225a: Einstein Probe detected of a fast X-ray transient
  58. GRB 250225B: Swift detection of a burst
  59. EP250223a: GROWTH-India Telescope optical observations
  60. GRB 250221A: Swift-BAT refined analysis
  61. EP250215A: J band upper limit by SYSU 80cm telescope
  62. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  63. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  64. EP250223a: Kinder optical follow-up observations
  65. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  66. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  67. GRB 250119B: VZLUSAT-2 detection
  68. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  69. GRB 250202B: VZLUSAT-2 detection
  70. GRB 250222A: SVOM/GRM observation of a burst
  71. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  72. GRB 250206A: VZLUSAT-2 detection
  73. EP250223a: REM NIR upper limit
  74. EP250223a: TRT optical afterglow observation
  75. EP250223a: refined analysis of the EP-WXT and FXT observations
  76. EP250223a: 1.6m Mephisto and 50cm array observations
  77. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  78. 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
  79. EP250223a: OASDG optical observations
  80. EP250223a: LCO detection of the afterglow
  81. EP250223a: Swift/XRT localization
  82. EP250223a: NOT optical afterglow candidate
  83. EP250223a: Einstein Probe detection of an X-ray transient
  84. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  85. GRB 250221A: Optical counterpart detection by LCO.
  86. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  87. GRB 250221A: GRANDMA/TAROT Detection
  88. GRB 250221A: Swift-XRT refined Analysis
  89. GRB 250221A: NOT optical observations
  90. GRB 250221A: 1.6m Mephisto optical detection
  91. GRB 250221A: AKO Optical Upper Limit
  92. GRB 250221A: Swift/UVOT Detection
  93. EP250220a: Liverpool Telescope upper limits
  94. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  95. GRB 250221A: REM optical/NIR afterglow detection
  96. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  97. GRB 250221A: Enhanced Swift-XRT position
  98. EP250220a: 1.6m Mephisto observations
  99. EP250220a: Liverpool Telescope optical upper limits
  100. EP250220a: Optical upper limit with Kinder observations

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