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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"

28284 results found.

  1. GRB 250313A: Fermi GBM Detection
  2. GRB 250312B: Fermi GBM Observation
  3. GRB 250313A: Swift-XRT observations
  4. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  5. GRB 250314A: SVOM detection of a burst
  6. GRB 250313A: AstroSat CZTI detection of a bright long burst
  7. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  8. GRB 250313A: Fermi-LAT detection
  9. EP250304a: Pan-STARRS r and i-band imaging and photometry
  10. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  11. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  12. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  13. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  14. GRB 250312A: Swift-XRT refined Analysis
  15. GRB 250312A: Enhanced Swift-XRT position
  16. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  17. GRB 250226B: Fermi GBM Observation
  18. GRB 250302A: Fermi GBM Observation
  19. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  20. GRB 250312A: Swift detection of a burst
  21. GRB 241213A: VIRT Optical Upper Limit
  22. GRB 241228A: VIRT Optical Upper Limit
  23. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  24. GRB 250311A: Swift-XRT observations
  25. GRB 250309B: 1.3m DFOT Optical observations
  26. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  28. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  29. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  30. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  31. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  32. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  33. GRB 250309B: PRIME near-infrared detection
  34. GRB 250225B: Swift-BAT refined analysis
  35. GRB 250311A/EP250311a: TRT optical upper limit
  36. EP250311a/GRB 250311A: EP-WXT detection
  37. GRB 250311B: SVOM detection of a burst
  38. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  39. GRB 250309B / AT2025dws: further SAO RAS optical observations
  40. EP250308a: 1.6m Mephisto optical upper limits
  41. Konus-Wind detection of GRB 250309B
  42. IPN triangulation of GRB 250308A (short)
  43. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  44. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  45. GRB 250309B: Swift-XRT refined Analysis
  46. GRB 250309B / IceCube-250309A: GECAM-B observations
  47. GRB 250309B / AT2025dws: SAO RAS optical observations
  48. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  49. GRB 250309B: Fermi GBM Observation
  50. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  51. IceCube-250309A: No candidates from the Zwicky Transient Facility
  52. Fermi-LAT gamma-ray observations of IceCube-250309A
  53. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  55. EP250308a: GSP optical upper limit
  56. EP250308a: Einstein Probe detection of an X-ray transient
  57. EP250308a: NOT optical upper limit
  58. GRB 250306A: EIRSAT-1 GMOD detection
  59. GRB 250306A: Swift-BAT refined analysis
  60. GRB 250306A: NuSTAR detection of the prompt emission
  61. EP250304a: MeerKAT detection of a possible radio counterpart
  62. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  63. GRB 250305A: AstroSat CZTI detection
  64. EP250302a:Xinglong optical observations
  65. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  66. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  67. GRB250101A: Radio upper limits from VLA observations
  68. GRB 250305A: SVOM/GRM observation of a burst
  69. The EP-WXT trigger 01709132323 is likely a flaring star
  70. EP250304A: Upper limits from Fermi-GBM Observations
  71. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  72. EP250302a: Optical Observations at CrAO and SAO RAS
  73. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  74. EP 250304A: Optical counterpart detection by LCO
  75. EP250302A: 1.3m DFOT optical afterglow detection
  76. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  77. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  78. EP250304a: REM NIR upper limits
  79. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  80. EP250302a: Mondy Continued Optical Observations
  81. EP250304a: Swift-XRT detection of a fading X-ray source
  82. EP250304a: TRT optical counterpart detection
  83. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  84. EP250304a: Einstein Probe detection of an X-ray transient
  85. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  86. EP250302a: SAO RAS optical observations
  87. EP250302a : GIT optical follow-up
  88. EP250225a: the candidate optical counterpart is an AGN
  89. EP250302a: Kinder optical follow-up observations
  90. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  91. EP250302a: Swift/UVOT detection
  92. EP250302a: optical observation from the INAF Asiago Observatory
  93. EP250302a: REM NIR upper limits
  94. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  95. EP250302a: Mondy Observations and Optical Light Curve
  96. EP250302a: VLT/MUSE optical redshift z = 1.131
  97. EP250302A: VLT near-infrared observations
  98. EP250302A: VLT/X-shooter tentative redshift
  99. EP250302a: OHP/T193 optical and spectroscopic observations
  100. EP250302a: Swift-XRT observations of a fading X-ray source

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