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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"

21921 results found.

  1. EP250304a: Pan-STARRS r and i-band imaging and photometry
  2. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  3. Fermi GRB 250313A: Global MASTER-Net observations report
  4. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  5. GRB 250312A: Enhanced Swift-XRT position
  6. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  7. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  8. GRB 250312A: Swift detection of a burst
  9. GRB 241213A: VIRT Optical Upper Limit
  10. GRB 241228A: VIRT Optical Upper Limit
  11. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  12. GRB 250309B: 1.3m DFOT Optical observations
  13. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  14. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  15. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  16. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  17. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  18. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  19. GRB 250309B: PRIME near-infrared detection
  20. GRB 250225B: Swift-BAT refined analysis
  21. GRB 250311A/EP250311a: TRT optical upper limit
  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. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  27. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  28. GRB 250309B / AT2025dws: SAO RAS optical observations
  29. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  30. GRB 250309B: Fermi GBM Observation
  31. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  32. IceCube-250309A: No candidates from the Zwicky Transient Facility
  33. EP250308a: Einstein Probe detection of an X-ray transient
  34. EP250308a: NOT optical upper limit
  35. Konus-Wind detection of GRB 250306A
  36. GRB 250306A: NuSTAR detection of the prompt emission
  37. EP250304a: MeerKAT detection of a possible radio counterpart
  38. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  39. EP250302a:Xinglong optical observations
  40. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  41. GRB250101A: Radio upper limits from VLA observations
  42. GRB 250305A: SVOM/GRM observation of a burst
  43. GRB 250305A: Fermi GBM Final Real-time Localization
  44. EP250302a: Optical Observations at CrAO and SAO RAS
  45. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  46. EP 250304A: Optical counterpart detection by LCO
  47. EP250302A: 1.3m DFOT optical afterglow detection
  48. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  49. Konus-Wind detection of GRB 250222A
  50. EP250304a: REM NIR upper limits
  51. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  52. EP250302a: Mondy Continued Optical Observations
  53. EP250304a: TRT optical counterpart detection
  54. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  55. EP250304a: Einstein Probe detection of an X-ray transient
  56. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  57. EP250302a: SAO RAS optical observations
  58. EP250302a : GIT optical follow-up
  59. EP250302a: Kinder optical follow-up observations
  60. EP250302a: Swift/UVOT detection
  61. EP250302a: optical observation from the INAF Asiago Observatory
  62. EP250302a: REM NIR upper limits
  63. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  64. EP250302a: Mondy Observations and Optical Light Curve
  65. EP250302a: VLT/MUSE optical redshift z = 1.131
  66. EP250302A: VLT near-infrared observations
  67. EP250302A: VLT/X-shooter tentative redshift
  68. EP250302a: OHP/T193 optical and spectroscopic observations
  69. EP250302a: Einstein Probe detection of an X-ray transient
  70. EP250302a: SVOM/C-GFT optical observations
  71. GRB 250226A: GRANDMA Optical Observations
  72. EP250302a: Montarrenti Observatory optical detection
  73. EP250302a: Nanshan/HMT optical counterpart detection
  74. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  75. GRB 250225B: VLT near-infrared afterglow confirmation
  76. EP250228a: Optical observations with Kinder and Swift/UVOT
  77. Konus-Wind detection of GRB 250226A
  78. GRB 250226A: KAO Optical Upper Limit
  79. GRB 250226A: AbAO AS-32 Optical Upper Limit
  80. EP250227a: TRT optical upper limit
  81. GRB 250225B: VLT/HAWKI near-infrared observations
  82. EP250227a: Optical upper limits with Kinder observations
  83. EP250227a: NOT optical observations
  84. EP250227a: Einstein Probe detected of a fast X-ray transient
  85. EP250228a: updates on the EP observations
  86. EP250223a: J band upper limit by SYSU 80cm telescope
  87. EP250228a: Einstein Probe detection of an X-ray transient
  88. GRB 250225B: VLT/Xshooter imaging
  89. GRB 250205A / EP250205A: further radio observations with the VLA
  90. EP250225a: NOT optical candidate counterpart
  91. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  92. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  93. EP250225a: TRT optical upper limits
  94. EP250226a/GRB 250226A: 1.6m Mephisto observations
  95. EP250226a/GRB 250226A: Kinder optical follow-up observations
  96. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  98. GRB 250225B: REM NIR upper limits
  99. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  100. Konus-Wind detection of GRB 250225B

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