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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"

28276 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 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  4. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  5. GRB 250312A: Swift-XRT refined Analysis
  6. GRB 250312A: Enhanced Swift-XRT position
  7. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  8. GRB 250226B: Fermi GBM Observation
  9. GRB 250302A: Fermi GBM Observation
  10. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  11. GRB 250312A: Swift detection of a burst
  12. GRB 241213A: VIRT Optical Upper Limit
  13. GRB 241228A: VIRT Optical Upper Limit
  14. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  15. GRB 250311A: Swift-XRT observations
  16. GRB 250309B: 1.3m DFOT Optical observations
  17. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  19. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  20. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  21. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  22. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  23. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  24. GRB 250309B: PRIME near-infrared detection
  25. GRB 250225B: Swift-BAT refined analysis
  26. GRB 250311A/EP250311a: TRT optical upper limit
  27. EP250311a/GRB 250311A: EP-WXT detection
  28. GRB 250311B: SVOM detection of a burst
  29. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  30. GRB 250309B / AT2025dws: further SAO RAS optical observations
  31. EP250308a: 1.6m Mephisto optical upper limits
  32. Konus-Wind detection of GRB 250309B
  33. IPN triangulation of GRB 250308A (short)
  34. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  35. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  36. GRB 250309B: Swift-XRT refined Analysis
  37. GRB 250309B / IceCube-250309A: GECAM-B observations
  38. GRB 250309B / AT2025dws: SAO RAS optical observations
  39. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  40. GRB 250309B: Fermi GBM Observation
  41. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  42. IceCube-250309A: No candidates from the Zwicky Transient Facility
  43. Fermi-LAT gamma-ray observations of IceCube-250309A
  44. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  46. EP250308a: GSP optical upper limit
  47. EP250308a: Einstein Probe detection of an X-ray transient
  48. EP250308a: NOT optical upper limit
  49. GRB 250306A: EIRSAT-1 GMOD detection
  50. GRB 250306A: Swift-BAT refined analysis
  51. GRB 250306A: NuSTAR detection of the prompt emission
  52. EP250304a: MeerKAT detection of a possible radio counterpart
  53. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  54. GRB 250305A: AstroSat CZTI detection
  55. EP250302a:Xinglong optical observations
  56. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  57. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  58. GRB250101A: Radio upper limits from VLA observations
  59. GRB 250305A: SVOM/GRM observation of a burst
  60. The EP-WXT trigger 01709132323 is likely a flaring star
  61. EP250304A: Upper limits from Fermi-GBM Observations
  62. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  63. EP250302a: Optical Observations at CrAO and SAO RAS
  64. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  65. EP 250304A: Optical counterpart detection by LCO
  66. EP250302A: 1.3m DFOT optical afterglow detection
  67. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  68. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  69. EP250304a: REM NIR upper limits
  70. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  71. EP250302a: Mondy Continued Optical Observations
  72. EP250304a: Swift-XRT detection of a fading X-ray source
  73. EP250304a: TRT optical counterpart detection
  74. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  75. EP250304a: Einstein Probe detection of an X-ray transient
  76. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  77. EP250302a: SAO RAS optical observations
  78. EP250302a : GIT optical follow-up
  79. EP250225a: the candidate optical counterpart is an AGN
  80. EP250302a: Kinder optical follow-up observations
  81. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  82. EP250302a: Swift/UVOT detection
  83. EP250302a: optical observation from the INAF Asiago Observatory
  84. EP250302a: REM NIR upper limits
  85. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  86. EP250302a: Mondy Observations and Optical Light Curve
  87. EP250302a: VLT/MUSE optical redshift z = 1.131
  88. EP250302A: VLT near-infrared observations
  89. EP250302A: VLT/X-shooter tentative redshift
  90. EP250302a: OHP/T193 optical and spectroscopic observations
  91. EP250302a: Swift-XRT observations of a fading X-ray source
  92. EP250302a: Einstein Probe detection of an X-ray transient
  93. EP250302a: SVOM/C-GFT optical observations
  94. GRB 250226A: GRANDMA Optical Observations
  95. EP250302a: Montarrenti Observatory optical detection
  96. EP250302a: Nanshan/HMT optical counterpart detection
  97. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  98. GRB 250225B: VLT near-infrared afterglow confirmation
  99. EP250228a: Optical observations with Kinder and Swift/UVOT
  100. Konus-Wind detection of GRB 250226A

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