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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"

31737 results found.

  1. EP240420a: NOT optical counterpart candidate and potential host
  2. GRB240419A: Skynet Optical Afterglow Analysis
  3. GRB240418A - Candidate afterglow from NIRES
  4. GRB 240419B: Swift/UVOT Upper Limits
  5. GRB 240419A: Swift/UVOT Upper Limits
  6. GRB 240419B: optical afterglow from the NOT
  7. EP240414a: Near-IR observations with NIRES and WINTER
  8. Swift GRB 240419B: Global MASTER-Net observations report
  9. EP240414A: Terskol Zeiss-2000 optical upper limit
  10. Swift GRB 240419A: Global MASTER-Net observations report
  11. GRB 240418A: Swift/UVOT Upper Limits
  12. GRB 240419A: REM NIR afterglow detection
  13. GRB 240411B: Swift/UVOT Detection
  14. EP240417a: YAHPT Optical Upper Limits
  15. GRB240418A: YAHPT Upper Limits
  16. GRB 240419A: VLT/UVES redshift of z = 5.178
  17. GRB 240419A: VLT optical afterglow detection
  18. EP240416a: J-band observations with WINTER
  19. EP240414a: GMG observation
  20. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  21. GRB 240418A: NOT optical upper limits
  22. GRB 240418A: AKO Upper Limit
  23. GRB 240411A: GOTO early optical upper limits
  24. Fermi GRB 240417A: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  26. EP240416A: Terskol Zeiss-2000 optical upper limit
  27. EP240416A: Khureltogoot optical upper limit
  28. Improved IPN triangulation of GRB 240411A
  29. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  30. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  31. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  32. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  33. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  34. GRB 240415A: Glowbug gamma-ray detection
  35. GRB 240414A: Glowbug gamma-ray detection
  36. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  37. GRB 240415B: GECAM-B detection
  38. EP 240416a: Xinglong and NOT decaying optical counterpart
  39. GRB 240415A: Swift-BAT refined analysis
  40. EP240416A: MASTER optical observations
  41. GRB 240411A: Glowbug gamma-ray detection
  42. GRB 240414A: Swift-BAT refined analysis
  43. EP240416a: Kinder optical counterpart candidate
  44. GRB 240414A: AbAO optical upprer limit
  45. GRB 240415A: Swift/UVOT Detection
  46. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  47. GRB 240415A: Fermi GBM Observation
  48. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  49. GRB 240415A: Earliest optical followup with the Kinder observations
  50. GRB 240414A: GMG observation
  51. EP240414a: EP-FXT follow-up observation
  52. GRB 240415B: Swift ToO observations
  53. GRB 240415A: OHP/T193 optical observations
  54. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  55. GRB 240415A: SAO RAS optical observations
  56. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  57. GRB 240414A: Fermi GBM Observation
  58. Fermi GRB 240415A: Global MASTER-Net observations report
  59. GRB 240415A: Mondy optical transient detection
  60. GRB 240414A: Photometric observation from 2.2m CAHA
  61. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  62. GRB 240414A: Swift/UVOT Detection
  63. LXT 240402A/GRB 240402B: Swift follow-up observations
  64. GRB 240414A: Mondy optical observations
  65. GRB 240414A: AKO Optical Upper Limit
  66. X-ray transient EP 240414a - GTC spectroscopic observations
  67. GRB 240415A: Prompt Swift-XRT observations
  68. GRB 240415A: Swift detection of a burst
  69. EP240413a: Upper limits from GECAM-B Observation
  70. EP 240414a: NOT optical counterpart confirmation
  71. GRB240414A : J-band upper limits from WINTER
  72. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  73. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  74. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  75. EP240413A: GOTO optical upper limits
  76. GRB 240414A: Skynet Optical Afterglow Observations
  77. Swift GRB 240414A: Global MASTER-Net observations report
  78. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  79. IPN triangulation of GRB 240410A
  80. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  81. IPN triangulation of GRB 240411A
  82. Fermi-LAT gamma-ray observations of IceCube-240412A
  83. GRB 240414A : MITSuME Akeno optical upper limits
  84. GRB 240414A: Redshift confirmation from GTC/OSIRIS+
  85. GRB 240414A : OHP/T193 redshift determination
  86. GRB 240414A : OHP/T193 optical counterpart detection
  87. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  88. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  89. EP240408a: GSP optical upper limit
  90. GRB 240411B: CrAO/ZTSh optical observations
  91. GRB 240411B: Kinder observations with Lulin observatory
  92. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  93. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  94. GRB 240411B: HiPERCAM/GTC observation
  95. GRB 240411B: Swift-BAT refined analysis
  96. GRB 240411B: 1.3m DFOT Optical observations
  97. GRB 240411A: GRBAlpha detection
  98. GRB 240411B: OHP/T193 optical observations
  99. GRB 240405A: Glowbug gamma-ray detection
  100. GRB 240411B: LCO optical afterglow detection

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