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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"

16159 results found.

  1. GRB 240811A: Bassano Bresciano Observatory upper limit
  2. GRB 240811A: Swift/UVOT Upper Limits
  3. EP240801a: Assy-Turgen optical observations
  4. GRB 240811A: LCOGT Optical Upper Limit
  5. GRB 240811A: Upper limits with Mephisto
  6. GRB240809A: Liverpool Telescope optical follow-up observations
  7. GRB 240809A: REM detection of the optical afterglow
  8. GRB 240809A: Bassano Bresciano Observatory optical observations
  9. GRB 240809A: Conclusive redshift from VLT
  10. GRB 240809A: KAIT optical observations
  11. GRB 240809A: GIT afterglow observations
  12. GRB 240809A: Tentative redshift from NOT
  13. GRB 240809A: JinShan optical observations
  14. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  15. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  16. EP240807a: STEP/T80S optical limits
  17. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  18. EP240802a/GRB240802A: KAIT optical upper limit
  19. EP240806A: Liverpool Telescope optical follow-up observations
  20. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  21. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  22. GRB 240805B: GIT optical upper limit
  23. EP240806a: KAIT optical observations
  24. EP240804a (GRB 240804B): NOT optical observations
  25. EP240806a: LCOGT optical counterpart detection
  26. GRB 240805B Bassano Bresciano Observatory upper limit
  27. GRB 240805B: JinShan optical afterglow detection
  28. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  29. EP240806a: EP-FXT detection of the X-ray emission
  30. EP 240806A: LCO optical observations
  31. EP240806a: GSP optical counterpart detection
  32. GRB 240805B: Optical detection with 1.6m Mephisto
  33. EP240804a: BOOTES-6/DPRT optical detection
  34. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  35. GRB 240805B: Swift/UVOT Upper Limits
  36. GRB 240805A: Swift/UVOT Upper Limits
  37. GRB 240805B: BTA optical afterglow candidate
  38. GRB 240805B: LCOGT Optical Upper Limits
  39. GRB 240805B: JinShan optical upper limits
  40. EP240801a: BTA BVRI photometry
  41. EP240804a: GSP detects optical candidate counterpart
  42. EP240801a: Continued optical observations at ZTSh (CraO)
  43. EP240804a: LCOGT optical counterpart detection
  44. EP240804a: NOT optical counterpart detection
  45. GRB 240805A: Swift detection of a burst
  46. EP240802a: Montarrenti Observatory optical upper limit
  47. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  48. EP240802A: Bassano Bresciano Observatory upper limit
  49. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  50. EP240801a: further SAO RAS optical observations
  51. EP240801a: optical observations at CrAO and AbAO
  52. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  53. EP240801a: Leavitt Observatory optical observations
  54. EP240801a: GTC spectroscopy and absorption redshift
  55. EP240801a: SAO RAS optical observations
  56. EP240801a: JinShan optical observations
  57. EP240801a: NOT optical observations
  58. EP240801a: follow-up observation with LCOGT
  59. EP240801a: GSP follow-up observations of the candidate counterpart
  60. EP240801a: Kinder follow-up observations of the candidate counterpart
  61. EP240801a: KAIT optical counterpart observations
  62. EP240801a: GMG observation
  63. EP240801a: TRT optical counterpart detection
  64. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  65. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  66. GRB240730A: BOOTES-5/JGT early optical upper limit
  67. GRB 240730A: KAIT Optical Upper Limit
  68. GRB 240730A: Swift/UVOT Upper Limits
  69. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  70. GRB 240727A: observations of optical counterpart.
  71. GRB 240727A: Swift/UVOT detection
  72. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  73. GRB 240727A: NOT optical observation
  74. GRB 240727A: JinShan optical upper limits
  75. GRB 240727A Bassano Bresciano Observatory upper limit
  76. GRB240529A: VIRT optical transient detection
  77. GRB240727A: Skynet Optical Afterglow Observations
  78. GRB 240727A: TRT optical afterglow detection
  79. GRB 240727A: KAIT Optical Afterglow Candidate
  80. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  81. GRB 240713A: 2.2m CAHA optical limit
  82. GRB 240715A: Swift/UVOT observations of the XRT sources.
  83. GRB240713A: Swift/UVOT Upper LImits
  84. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  85. GRB 240713A: LAST optical upper limit
  86. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  87. GRB 240712A ATCA radio observations
  88. GRB240715A: GRANDMA Optical Upper Limits
  89. GRB 240712A: Swift/UVOT Upper Limits
  90. EP-WXT flaring star and the optical flaring activity during its decay phase
  91. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  92. The EP-WXT source triggered on July 14th is likely a flaring star
  93. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  94. GRB 240713A: JinShan optical upper limits
  95. GRB 240713A: OHP/T120 optical upper limit
  96. GRB240713A: Optical upper limit with Kinder observations
  97. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  98. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  99. EP240708a: GSP optical upper limit
  100. EP240708a: KAIT optical upper limit

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