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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"

26727 results found.

  1. GRB 250309B: PRIME near-infrared detection
  2. EP250304a: Chandra detection
  3. GRB 250225B: Swift-BAT refined analysis
  4. GRB 250311A/EP250311a: TRT optical upper limit
  5. EP250311a/GRB 250311A: EP-WXT detection
  6. GRB 250311B: SVOM detection of a burst
  7. GRB 250309B / AT2025dws: further SAO RAS optical observations
  8. IceCube-250309A: Upper limits from Fermi-GBM Observations
  9. EP250308a: 1.6m Mephisto optical upper limits
  10. Konus-Wind detection of GRB 250309B
  11. IPN triangulation of GRB 250308A (short)
  12. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  13. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  14. GRB 250309B: Swift-XRT refined Analysis
  15. GRB 250309B / IceCube-250309A: GECAM-B observations
  16. GRB 250309B / AT2025dws: SAO RAS optical observations
  17. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  18. GRB 250309B: Fermi GBM Observation
  19. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  20. IceCube-250309A: No candidates from the Zwicky Transient Facility
  21. Fermi-LAT gamma-ray observations of IceCube-250309A
  22. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  23. EP250308a: Einstein Probe detection of an X-ray transient
  24. EP250308a: NOT optical upper limit
  25. EP250304a: MeerKAT detection of a possible radio counterpart
  26. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  27. EP250302a:Xinglong optical observations
  28. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  29. GRB250101A: Radio upper limits from VLA observations
  30. GRB 250305A: SVOM/GRM observation of a burst
  31. The EP-WXT trigger 01709132323 is likely a flaring star
  32. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  33. EP250302a: Optical Observations at CrAO and SAO RAS
  34. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  35. EP 250304A: Optical counterpart detection by LCO
  36. EP250302A: 1.3m DFOT optical afterglow detection
  37. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  38. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  39. Konus-Wind detection of GRB 250222A
  40. EP250304a: REM NIR upper limits
  41. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  42. EP250302a: Mondy Continued Optical Observations
  43. EP250304a: Swift-XRT detection of a fading X-ray source
  44. EP250304a: TRT optical counterpart detection
  45. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  46. EP250304a: Einstein Probe detection of an X-ray transient
  47. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  48. EP250302a: SAO RAS optical observations
  49. EP250302a : GIT optical follow-up
  50. EP250302a: Kinder optical follow-up observations
  51. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  52. EP250302a: Swift/UVOT detection
  53. EP250302a: optical observation from the INAF Asiago Observatory
  54. EP250302a: REM NIR upper limits
  55. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  56. EP250302a: Mondy Observations and Optical Light Curve
  57. EP250302a: VLT/MUSE optical redshift z = 1.131
  58. EP250302A: VLT near-infrared observations
  59. EP250302A: VLT/X-shooter tentative redshift
  60. EP250302a: OHP/T193 optical and spectroscopic observations
  61. EP250302a: Swift-XRT observations of a fading X-ray source
  62. EP250302a: Einstein Probe detection of an X-ray transient
  63. EP250302a: SVOM/C-GFT optical observations
  64. GRB 250226A: GRANDMA Optical Observations
  65. EP250302a: Montarrenti Observatory optical detection
  66. EP250302a: Nanshan/HMT optical counterpart detection
  67. GRB 250302A: Fermi GBM Final Real-time Localization
  68. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  69. GRB 250225B: VLT near-infrared afterglow confirmation
  70. EP250228a: Optical observations with Kinder and Swift/UVOT
  71. GRB 250226A: KAO Optical Upper Limit
  72. GRB 250226A: AbAO AS-32 Optical Upper Limit
  73. EP250227a: TRT optical upper limit
  74. GRB 250225B: VLT/HAWKI near-infrared observations
  75. EP250227a: Optical upper limits with Kinder observations
  76. EP250227a: NOT optical observations
  77. EP250227a: Einstein Probe detected of a fast X-ray transient
  78. EP250228a: updates on the EP observations
  79. GRB 250226A: Fermi GBM Observation
  80. EP250225a: EP-FXT follow-up observation
  81. EP250223a: J band upper limit by SYSU 80cm telescope
  82. EP250228a: Swift/XRT localisation
  83. EP250228a: Einstein Probe detection of an X-ray transient
  84. GRB 250225B: VLT/Xshooter imaging
  85. GRB 250205A / EP250205A: further radio observations with the VLA
  86. EP250225a: NOT optical candidate counterpart
  87. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  88. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  89. EP250225a: TRT optical upper limits
  90. EP250226a/GRB 250226A: 1.6m Mephisto observations
  91. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  92. EP250226a/GRB 250226A: Kinder optical follow-up observations
  93. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  94. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  95. GRB 250225B: Fermi GBM Observation
  96. GRB 250225B: REM NIR upper limits
  97. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  98. Konus-Wind detection of GRB 250225B
  99. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  100. EP250223a: CrAO ZTSH optical observation

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