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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"

20517 results found.

  1. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  2. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  3. GRB 250312A: Enhanced Swift-XRT position
  4. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  5. GRB 250312A: Swift detection of a burst
  6. GRB 241213A: VIRT Optical Upper Limit
  7. GRB 241228A: VIRT Optical Upper Limit
  8. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  9. GRB 250311A: Swift-XRT observations
  10. GRB 250309B: 1.3m DFOT Optical observations
  11. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  12. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  13. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  14. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  15. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  16. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  17. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  18. GRB 250309B: PRIME near-infrared detection
  19. GRB 250225B: Swift-BAT refined analysis
  20. GRB 250311A/EP250311a: TRT optical upper limit
  21. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  22. EP250311a/GRB 250311A: EP-WXT detection
  23. GRB 250309B / AT2025dws: further SAO RAS optical observations
  24. EP250308a: 1.6m Mephisto optical upper limits
  25. IPN triangulation of GRB 250308A (short)
  26. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  27. GRB 250309B / AT2025dws: SAO RAS optical observations
  28. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  29. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  30. IceCube-250309A: No candidates from the Zwicky Transient Facility
  31. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  32. EP250308a: Einstein Probe detection of an X-ray transient
  33. EP250308a: NOT optical upper limit
  34. EP250304a: MeerKAT detection of a possible radio counterpart
  35. EP250302a:Xinglong optical observations
  36. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  37. GRB250101A: Radio upper limits from VLA observations
  38. GRB 250305A: SVOM/GRM observation of a burst
  39. EP250302a: Optical Observations at CrAO and SAO RAS
  40. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  41. EP 250304A: Optical counterpart detection by LCO
  42. EP250302A: 1.3m DFOT optical afterglow detection
  43. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  44. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP250304a: REM NIR upper limits
  46. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  47. EP250302a: Mondy Continued Optical Observations
  48. EP250304a: VLT/X-shooter redshift z = 0.200
  49. EP250304a: TRT optical counterpart detection
  50. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  51. EP250304a: Einstein Probe detection of an X-ray transient
  52. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  53. EP250302a: SAO RAS optical observations
  54. EP250302a : GIT optical follow-up
  55. EP250302a: Kinder optical follow-up observations
  56. EP250302a: Swift/UVOT detection
  57. EP250302a: NUTTelA-TAO Early Measurments
  58. EP250302a: optical observation from the INAF Asiago Observatory
  59. EP250302a: REM NIR upper limits
  60. EP250302a: Mondy Observations and Optical Light Curve
  61. EP250302a: VLT/MUSE optical redshift z = 1.131
  62. EP250302A: VLT near-infrared observations
  63. EP250302A: VLT/X-shooter tentative redshift
  64. EP250302a: OHP/T193 optical and spectroscopic observations
  65. EP250302a: Einstein Probe detection of an X-ray transient
  66. EP250302a: SVOM/C-GFT optical observations
  67. GRB 250226A: GRANDMA Optical Observations
  68. EP250302a: Montarrenti Observatory optical detection
  69. EP250302a: Nanshan/HMT optical counterpart detection
  70. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  71. GRB 250225B: VLT near-infrared afterglow confirmation
  72. EP250228a: Optical observations with Kinder and Swift/UVOT
  73. GRB 250226A: KAO Optical Upper Limit
  74. GRB 250226A: AbAO AS-32 Optical Upper Limit
  75. EP250227a: TRT optical upper limit
  76. GRB 250225B: VLT/HAWKI near-infrared observations
  77. EP250227a: Optical upper limits with Kinder observations
  78. EP250227a: NOT optical observations
  79. EP250227a: Einstein Probe detected of a fast X-ray transient
  80. EP250228a: updates on the EP observations
  81. EP250223a: J band upper limit by SYSU 80cm telescope
  82. EP250228a: Einstein Probe detection of an X-ray transient
  83. GRB 250225B: VLT/Xshooter imaging
  84. GRB 250205A / EP250205A: further radio observations with the VLA
  85. EP250225a: NOT optical candidate counterpart
  86. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  87. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  88. EP250225a: TRT optical upper limits
  89. EP250226a/GRB 250226A: 1.6m Mephisto observations
  90. EP250226a/GRB 250226A: Kinder optical follow-up observations
  91. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  92. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  94. GRB 250221A: ATCA Detections and Upper Limits
  95. GRB 250225B: REM NIR upper limits
  96. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  97. EP250223a: CrAO ZTSH optical observation
  98. GRB 250225B: VLT optical and near-infrared candidate counterpart
  99. GRB 250225B: SVOM/GRM observation of a long burst
  100. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart

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