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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.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

19142 results found.

  1. GRB 250108B: Gemini-North likely redshift z = 2.197
  2. GRB 250108B: 1.3m DFOT upper limit
  3. GRB 250108B: REM optical/NIR upper limits
  4. EP250109a: SVOM/VT optical candidate
  5. EP250109a: Global MASTER-Net observations report
  6. GRB 250101A: Terskol K-800 optical observations
  7. EP250109a: GOTO optical upper limits
  8. GRB 250108A: Swift/UVOT Upper Limits
  9. EP250108a: Global MASTER-Net observations report
  10. EP250109a: EP-WXT detection of an X-ray transient
  11. GRB 250108A: NOT optical upper limit
  12. EP250108a: EP-WXT detection of an X-ray transient
  13. Swift GRB 250108B: Global MASTER-Net observations report
  14. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  15. GRB 250103A: 1.6m Mephisto optical observations
  16. GRB 250108A: Swift-XRT afterglow detection
  17. GRB 250108A:SVOM/VT optical candidate
  18. GRB 250108B: Swift/UVOT Upper Limits
  19. GRB 250103A: Swift-XRT afterglow detection
  20. GRB 250108A: Swift ToO observations
  21. Fermi GRB 250107B: Global MASTER-Net observations report
  22. GRB 250107A: Swift ToO observations
  23. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  24. GRB 250106A: SVOM/VT 2nd optical deep observation
  25. GRB 250101A: J band upper limit by SYSU 80cm telescope
  26. EPWXT01709129925: Xinglong optical observations
  27. GRB 250106A: NOT optical observations
  28. GRB 250103B: REM optical/NIR upper limits
  29. GRB 250101A: REM optical/NIR counterpart detection
  30. GRB 250106A: Swift-XRT observations
  31. GRB 250106A: SVOM/VT optical candidate
  32. GRB 250106A: Swift ToO observations
  33. GRB 250106A: SVOM detection of a long burst
  34. Fermi trigger No 757753930: Global MASTER-Net observations report
  35. GRB 241229A: SVOM/VT optical upperlimit
  36. GRB 250103A: Bassano Bresciano Observatory upper limit
  37. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  38. GRB 250103A: Swift-XRT observations
  39. GRB 250101A: 1.3m DFOT optical afterglow detection
  40. GRB 241229A: 1.3m DFOT upper limit
  41. GRB 241228B: 1.3m DFOT Optical observations
  42. GRB 241228A: 1.3m DFOT upper limit
  43. GRB 250103A: NOT spectroscopic redshift
  44. GRB 250103B:SVOM/VT optical counterpart
  45. GRB 250103A: Montarrenti Observatory optical detection
  46. GRB 250101A: further LCOGT optical afterglow observations
  47. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  48. GRB 250103A: NOT optical observations
  49. Swift GRB 250103B: Global MASTER-Net observations report
  50. GRB 250103A: SVOM/VT optical counterpart confirmation
  51. GRB 250103A: Swift ToO observations
  52. GRB 250101a: Liverpool Telescope optical follow-up
  53. Fermi GRB 250102A: Global MASTER-Net observations report
  54. GRB 250103A: GOTO optical upper limit
  55. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  56. IceCube Alert 250102.58: Global MASTER-Net observations report
  57. EP241231b: optical upper limit with the Liverpool Telescope
  58. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  59. GRB 250101A: further SAO RAS optical observations
  60. GRB 250101A: LCO optical counterpart detection
  61. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  62. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  63. GRB 250101A: Swift/UVOT Detection
  64. GRB 250101A: 1.6m Mephisto multi-band optical followup
  65. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  66. GRB 250101A: LCOGT optical afterglow detection
  67. GRB 250101A: OASDG optical observations
  68. Fermi GRB 250101B: Global MASTER-Net observations report
  69. GRB 250101A: SAO RAS observations of optical brightening
  70. GRB 250101A: SAO RAS optical observations
  71. GRB 250101A: SVOM/C-GFT early optical observations
  72. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  73. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  74. GRB 250101A: Nanshan/HMT optical observations
  75. GRB 250101A : GIT optical detection
  76. Swift GRB250101.56: Global MASTER-Net observations report
  77. GRB 241217a/EP241217b: ATCA Radio Detection
  78. EP241217a: VLA Radio Detection

  79. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  80. GRB 241229B: Continued CrAO ZTSh observations
  81. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  82. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  83. GRB 241229A: EP-FXT X-ray afterglow confirmation
  84. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  85. EP241217A: J band upper limit by SYSU 80cm telescope
  86. GRB 241228B: SAO RAS optical observations
  87. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  88. GRB 241229A: SAO RAS optical observations
  89. GRB 241229B: SVOM/VT optical candidate
  90. GRB 241229A: Swift-XRT observations
  91. EP240702a: 7DT Optical upper limits
  92. GRB 240606B: 7DT Optical upper limits
  93. Fermi trigger No 757231333: Global MASTER-Net observations report
  94. GRB241229B: UVOT upper limits
  95. GRB 241228B: D50 optical detection
  96. GRB 241228B: Fermi GBM Observation
  97. GRB 241228B: Swift-XRT afterglow detection
  98. GRB 241229A: Swift ToO observations
  99. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  100. GRB 241228A: Mondy optical afterglow observations

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