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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

16239 results found.

  1. EP240626a: EP-FXT detection of the X-ray emission
  2. EP240626a: EP-WXT detection of a fast X-ray transient
  3. GRB 240625A: Fermi GBM Observation
  4. EP240625a: NOT optical counterpart candidate
  5. EP240625a: EP-FXT detection of the X-ray emission
  6. EP240625a: EP-WXT detection of a fast X-ray transient
  7. GRB240615A: Gemini-North observations of the BAT and XRT positions
  8. GRB240615A: Gemini-North observations of the BAT and XRT positions
  9. GRB 240619A: detection of a radio counterpart with AMI-LA
  10. GRB 240619A: J-band detection with WINTER
  11. EP240618a: NOT optical counterpart candidate
  12. GRB 240529A: JinShan optical observations
  13. X-ray transient EP240618a: Fermi/GBM non-detection
  14. GRB 240615A: NOT optical observations
  15. EP240618a: TRT optical upper limit
  16. EP240617a: STEP/T80S optical limits
  17. GRB 240615A: possible transient detection from Wendelstein observations
  18. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  19. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  20. GRB240615A: 1.3m DFOT optical upper limit
  21. EP240617a: EP-WXT detection of a fast X-ray transient
  22. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  23. GRB 240615A: J-band upper limits from WINTER
  24. GRB240529A: 3.6m TNG NIR detection 8d after the burst
  25. GRB 240529A: LBT optical detection and late temporal decay
  26. GRB 240529A : MITSuME Akeno optical afterglow detection
  27. Trigger 1236151: Swift detection of EXO 0748-676
  28. IPN triangulation of GRB 240607A
  29. Swift Trigger 1235109: consistent with noise and not astrophysical
  30. GRB 240529A: radio detection with AMI-LA
  31. GRB 240606B: Swift-XRT afterglow detection
  32. Swift Trigger 1235109: a possible GRB 240606A
  33. GRB 240529A: SAO RAS optical observations
  34. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  35. Fermi GRB 240603C: Global MASTER-Net observations report
  36. GRB 240529A: MASTER prompt OT detection
  37. GRB 240529A: continued SAO RAS optical observations
  38. The EP-WXT source triggered on June 1st is likely a flaring star
  39. GRB 240529A: further SAO RAS optical observations
  40. Swift Trigger 1232465 is not a GRB
  41. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  42. GRB 240529A: 1.3m DFOT Optical observations
  43. GRB 240529A : Mondy optical observations
  44. GRB 240529A: SAO RAS optical observations
  45. GRB 240529A: GROWTH-India optical follow-up
  46. GRB 240529A: T193/MISTRAL observations
  47. GRB 240529A: Redshift from GTC/OSIRIS+
  48. GRB 240529A: AKO Optical Afterglow Detection
  49. LIGO/Virgo/KAGRA S240530a: Identification of a GW compact binary merger candidate
  50. GRB 240529A: J-band detections with WINTER
  51. GRB 240529A: Skynet Optical Observations
  52. LXT 240528A: LEIA detection of a fast X-ray transient
  53. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  54. GRB 240529A: Swift/UVOT Detection
  55. GRB 240529A: NOT optical observations
  56. GRB 240527B: Swift-XRT afterglow detection
  57. GRB 240529A: Enhanced Swift-XRT position
  58. GRB 240529A: Swift detection of a burst with an optical counterpart
  59. LIGO/Virgo/KAGRA S240525p: Identification of a GW compact binary merger candidate
  60. GRB 240523A: Enhanced Swift-XRT position
  61. GRB 240523A: Swift detection of a burst
  62. GRB 240521A: GECAM-B detection of a long burst
  63. GRB 240516B: AstroSat CZTI detection
  64. GRB 240502A: VZLUSAT-2 detection
  65. GRB 240516A: Swift/UVOT Upper Limits
  66. EP240518a: possibly identified with a flare star by EP-FXT
  67. EP240518a: EP-WXT detection of a new X-ray transient
  68. GRB 240516A ATCA radio observations
  69. IPN triangulation of GRB 240514B (short)
  70. GRB 240511A: Observations from GTC/OSIRIS+
  71. GRB 240516A: Swift detection of a burst
  72. GRB 240511A: radio detection of afterglow candidate
  73. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  74. GRB 240511A: J-band observations with WINTER
  75. GRB 240511A: Enhanced Swift-XRT position
  76. GRB 240511A : MITSuME Akeno optical upper limits
  77. GRB 240511A: Swift-XRT refined Analysis
  78. GRB 240511A: Swift detection of a burst
  79. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  80. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  81. EP240506a: Xinglong optical upper limit
  82. EP240506a: Archival radio searching
  83. EP240506a: TRT optical upper limit
  84. EP240506a: Optical upper limit with Kinder observations
  85. IPN triangulation of GRB 240504A
  86. GRB 240502A: 1.3m DFOT Optical upper limit
  87. EP240506a: EP-WXT detection of a new fast X-ray transient
  88. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  89. GW170817: VLA observations at ~5.5 yrs since merger
  90. GRB 240415A 1.3m DFOT Optical upper limit
  91. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  92. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  93. Fermi-LAT gamma-ray observations of IceCube-240424A
  94. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  95. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  96. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  97. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  98. EP240426b: AST3-2 optical upper limit
  99. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  100. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a

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