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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"
  1. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  2. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  3. IceCube-Cascade 240416A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 240417A: Fermi GBM Final Real-time Localization
  5. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  6. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  7. GRB 240415A: Glowbug gamma-ray detection
  8. GRB 240414A: Glowbug gamma-ray detection
  9. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  10. GRB 240415B: GECAM-B detection
  11. EP 240416a: Xinglong and NOT decaying optical counterpart
  12. GRB 240415A: Swift-BAT refined analysis
  13. EP240416A: MASTER optical observations
  14. GRB 240411A: Glowbug gamma-ray detection
  15. GRB 240414A: Swift-BAT refined analysis
  16. EP240416a: Kinder optical counterpart candidate
  17. EP240416a: EP-WXT detection of a fast X-ray transient
  18. GRB 240414A: AbAO optical upprer limit
  19. GRB 240415A: Swift/UVOT Detection
  20. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  21. GRB 240415A: Fermi GBM Observation
  22. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  23. GRB 240415A: Earliest optical followup with the Kinder observations
  24. GRB 240414A: GMG observation
  25. EP 240414a: BOOTES-4/MET Optical Upper Limits
  26. EP240414a: EP-FXT follow-up observation
  27. GRB 240415A: Enhanced Swift-XRT position
  28. GRB 240415B: Swift ToO observations
  29. GRB 240415B: Swift/BAT-GUANO Correction
  30. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  31. GRB 240415A: OHP/T193 optical observations
  32. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  33. GRB 240415A: SAO RAS optical observations
  34. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  35. GRB 240414A: Fermi GBM Observation
  36. Fermi GRB 240415A: Global MASTER-Net observations report
  37. GRB 240415A: Mondy optical transient detection
  38. GRB 240414A: Photometric observation from 2.2m CAHA
  39. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 240414A: Swift/UVOT Detection
  41. LXT 240402A/GRB 240402B: Swift follow-up observations
  42. GRB 240414A: Mondy optical observations
  43. GRB 240414B: Fermi GBM Final Real-time Localization
  44. GRB 240414A: AKO Optical Upper Limit
  45. X-ray transient EP 240414a - GTC spectroscopic observations
  46. GRB 240415A: Prompt Swift-XRT observations
  47. GRB 240415A: Swift detection of a burst
  48. GRB 240415A: Fermi GBM Final Real-time Localization
  49. EP240413a: Upper limits from GECAM-B Observation
  50. EP 240414a: NOT optical counterpart confirmation
  51. GRB 240414A: Swift-XRT refined Analysis
  52. GRB240414A : J-band upper limits from WINTER
  53. GRB 240414A: Enhanced Swift-XRT position
  54. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  55. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  56. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  57. EP240413A: GOTO optical upper limits
  58. GRB 240414A: Skynet Optical Afterglow Observations
  59. Fermi trigger No 734754044: Global MASTER-Net observations report
  60. Swift GRB 240414A: Global MASTER-Net observations report
  61. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  62. IPN triangulation of GRB 240410A
  63. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  64. EP240414a: EP-WXT detection of a fast X-ray transient
  65. IPN triangulation of GRB 240411A
  66. Fermi-LAT gamma-ray observations of IceCube-240412A
  67. GRB 240414A : MITSuME Akeno optical upper limits
  68. GRB 240414A: Redshift confirmation from GTC/OSIRIS+
  69. EP240413a: EP-WXT detection of a fast X-ray transient
  70. GRB 240414A : OHP/T193 redshift determination
  71. GRB 240414A : OHP/T193 optical counterpart detection
  72. GRB 240414A: Swift detection of a burst
  73. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  74. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  76. EP240408a: GSP optical upper limit
  77. GRB 240411B: CrAO/ZTSh optical observations
  78. GRB 240411B: Kinder observations with Lulin observatory
  79. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  80. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  81. GRB 240411B: HiPERCAM/GTC observation
  82. IceCube Alert 240412.23: Global MASTER-Net observations report
  83. GRB 240411B: Swift-BAT refined analysis
  84. GRB 240411B: Swift-XRT refined Analysis
  85. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 240411B: 1.3m DFOT Optical observations
  87. GRB 240411A: GRBAlpha detection
  88. GRB 240411B: OHP/T193 optical observations
  89. GRB 240405A: Glowbug gamma-ray detection
  90. GRB 240411B: Enhanced Swift-XRT position
  91. GRB 240411B: LCO optical afterglow detection
  92. GRB 240411B: Swift detection of a burst
  93. GRB 240408B: GRBAlpha detection
  94. GRB 240411A: Fermi GBM Final Real-time Localization
  95. EP240408A: MASTER optical observations
  96. EP240408a: GROND detection of a candidate counterpart
  97. EP240408a: Upper limits from GECAM-B Observation
  98. EP240408a: Swift follow-up observation
  99. EP240408a: BOOTES-6/DPRT optical upper limit
  100. X-ray transient EP240315a: second epoch e-MERLIN radio observations

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