Three weeks after the Thirty Meter Telescope was granted its construction permit, the developer and eventual operator of the planned $1.4 billion cutting-edge observatory says it is still evaluating its next move.

“No decisions have been made at this point to move ahead with TMT construction on Mauna Kea,” TMT spokesman Scott Ishikawa said Thursday. “We are still assessing next steps, and there’s a lot to consider. Nevertheless, we remain committed to building in Hawaii.”

Meanwhile, TMT opponents say they are preparing to file an appeal to the state Board of Land and Natural Resource’s Sept. 28 decision to issue the project’s conservation district use permit.

“We are definitely going to appeal,” said Kealoha Pisciotta, leader of the Mauna Kea Hui and one of the petitioners in the case.

TMT foes have until Nov. 3 to file — a date that represents 30 days after receipt of a certified copy of the Land Board’s decision, officials said.

The appeal will go directly to the Hawaii Supreme Court under the terms of Act 48, a fast-track provision approved by the 2016 state Legislature with the TMT in mind.

The law requires the high court to give priority to select contested case appeals of significant statewide importance.

During last month’s final contested case arguments before the Land Board, several petitioners urged the board to include a requirement delaying the start of construction until after the high court hears an appeal.

The board declined to add a “stay” condition, prompting several TMT opponents to worry aloud that construction might begin before the litigation was completed.

Three years ago the state Supreme Court granted a stay halting construction pending its ruling — a decision that invalidated the project’s construction permit. The court said the Land Board “put the cart before the horse” when it approved the permit prior to holding the contested case hearing.

This year’s contested case replay included 23 parties and lasted 44 days over several months, producing some 800 exhibits and more than 550 documents. In the end, former Circuit Judge Riki May Amano recommended approval.

Joshua Wisch, special assistant to state Attorney General Douglas Chin, said that before TMT International Observatory LLC can begin construction, it first needs a “notice to proceed” from the state.

The lessee, the University of Hawaii at Hilo, is now working on a plan to implement the 43 conditions imposed by the Land Board on the construction permit, spokesman Dan Meisenzahl said.

A potential stumbling block is the project’s 6-acre sublease, which was invalidated by Hawaii island Circuit Judge Greg Nakamura in January. Nakamura ruled that the board violated the constitutional rights of E. Kalani Flores of Hilo by denying his request to a contested case hearing in 2014 prior to allowing the university to issue the 6-acre sublease to TMT.

The state, which opposed the ruling, has appealed the case to the state Supreme Court. Briefings have been filed in the case, and the next move — whether it’s scheduling oral arguments, issuing a ruling or waiting to combine the case with the TMT appeal — is up to the court.

David Kauila Kopper, the Native Hawaiian Legal Corp. attorney who represents Flores, said he believes it would be improper for TMT to begin construction without a valid sublease.

Looming over these events is TMT’s self-­imposed deadline. The board of the California nonprofit, with partners in India, Canada, Japan and China, continues to insist on starting construction in April, whether it’s on Hawaii’s tallest mountain or an alternative peak on La Palma in the Canary Islands.